octeontx2-af: fix build regression without CONFIG_DCB

When DCB is disabled, the pfc_en struct member cannot be accessed:

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c: In function 'otx2_is_pfc_enabled':
drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c:22:48: error: 'struct otx2_nic' has no member named 'pfc_en'
   22 |         return IS_ENABLED(CONFIG_DCB) && !!pfvf->pfc_en;
      |                                                ^~
drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c: In function 'otx2_nix_config_bp':
drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c:1755:33: error: 'IEEE_8021QAZ_MAX_TCS' undeclared (first use in this function)
 1755 |                 req->chan_cnt = IEEE_8021QAZ_MAX_TCS;
      |                                 ^~~~~~~~~~~~~~~~~~~~

Move the member out of the #ifdef block to avoid putting back another
check in the source file and add the missing include file unconditionally.

Fixes: a7ef63d ("octeontx2-af: Disable backpressure between CPT and NIX")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241213083228.2645757-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c

@@ -10,6 +10,7 @@
 #include <net/page_pool/helpers.h>
 #include <net/tso.h>
 #include <linux/bitfield.h>
+#include <linux/dcbnl.h>
 #include <net/xfrm.h>
 
 #include "otx2_reg.h"

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h

@@ -505,9 +505,9 @@ struct otx2_nic {
 
 	/* Devlink */
 	struct otx2_devlink	*dl;
-#ifdef CONFIG_DCB
 	/* PFC */
 	u8			pfc_en;
+#ifdef CONFIG_DCB
 	u8			*queue_to_pfc_map;
 	u16			pfc_schq_list[NIX_TXSCH_LVL_CNT][MAX_TXSCHQ_PER_FUNC];
 	bool			pfc_alloc_status[NIX_PF_PFC_PRIO_MAX];