net: axienet: Fix kernel doc warnings

Add description of mdio enable, mdio disable and mdio wait functions.
Add description of skb pointer in axidma_bd data structure.
Remove 'phy_node' description in axienet local data structure since
it is not a valid struct member.
Correct description of struct axienet_option.

Fix below kernel-doc warnings in drivers/net/ethernet/xilinx/:
1) xilinx_axienet_mdio.c:1: warning: no structured comments found
2) xilinx_axienet.h:379: warning: Function parameter or struct member
'skb' not described in 'axidma_bd'
3) xilinx_axienet.h:538: warning: Excess struct member 'phy_node'
description in 'axienet_local'
4) xilinx_axienet.h:1002: warning: expecting prototype for struct
axiethernet_option. Prototype was for struct axienet_option instead

Signed-off-by: Suraj Gupta <suraj.gupta2@amd.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Link: https://lore.kernel.org/r/20240328110713.12885-1-suraj.gupta2@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/xilinx/xilinx_axienet.h

@@ -359,6 +359,7 @@
  * @app2:         MM2S/S2MM User Application Field 2.
  * @app3:         MM2S/S2MM User Application Field 3.
  * @app4:         MM2S/S2MM User Application Field 4.
+ * @skb:          Pointer to SKB transferred using DMA
  */
 struct axidma_bd {
 	u32 next;	/* Physical address of next buffer descriptor */
@@ -399,7 +400,6 @@ struct skbuf_dma_descriptor {
  * struct axienet_local - axienet private per device data
  * @ndev:	Pointer for net_device to which it will be attached.
  * @dev:	Pointer to device structure
- * @phy_node:	Pointer to device node structure
  * @phylink:	Pointer to phylink instance
  * @phylink_config: phylink configuration settings
  * @pcs_phy:	Reference to PCS/PMA PHY if used
@@ -537,7 +537,7 @@ struct axienet_local {
 };
 
 /**
- * struct axiethernet_option - Used to set axi ethernet hardware options
+ * struct axienet_option - Used to set axi ethernet hardware options
  * @opt:	Option to be set.
  * @reg:	Register offset to be written for setting the option
  * @m_or:	Mask to be ORed for setting the option in the register

drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c

@@ -20,7 +20,14 @@
 #define DEFAULT_MDIO_FREQ	2500000 /* 2.5 MHz */
 #define DEFAULT_HOST_CLOCK	150000000 /* 150 MHz */
 
-/* Wait till MDIO interface is ready to accept a new transaction.*/
+/**
+ * axienet_mdio_wait_until_ready - MDIO wait function
+ * @lp:	Pointer to axienet local data structure.
+ *
+ * Return :	0 on success, Negative value on errors
+ *
+ * Wait till MDIO interface is ready to accept a new transaction.
+ */
 static int axienet_mdio_wait_until_ready(struct axienet_local *lp)
 {
 	u32 val;
@@ -30,14 +37,24 @@ static int axienet_mdio_wait_until_ready(struct axienet_local *lp)
 				  1, 20000);
 }
 
-/* Enable the MDIO MDC. Called prior to a read/write operation */
+/**
+ * axienet_mdio_mdc_enable - MDIO MDC enable function
+ * @lp:	Pointer to axienet local data structure.
+ *
+ * Enable the MDIO MDC. Called prior to a read/write operation
+ */
 static void axienet_mdio_mdc_enable(struct axienet_local *lp)
 {
 	axienet_iow(lp, XAE_MDIO_MC_OFFSET,
 		    ((u32)lp->mii_clk_div | XAE_MDIO_MC_MDIOEN_MASK));
 }
 
-/* Disable the MDIO MDC. Called after a read/write operation*/
+/**
+ * axienet_mdio_mdc_disable - MDIO MDC disable function
+ * @lp:	Pointer to axienet local data structure.
+ *
+ * Disable the MDIO MDC. Called after a read/write operation
+ */
 static void axienet_mdio_mdc_disable(struct axienet_local *lp)
 {
 	u32 mc_reg;