soc: ti: k3-ringacc: Provide documentation for 'k3_ring's 'state'

Fixes the following W=1 kernel build warning(s):

 drivers/soc/ti/k3-ringacc.c:163: warning: Function parameter or member 'state' not described in 'k3_ring'

Cc: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

drivers/soc/ti/k3-ringacc.c

@@ -137,6 +137,7 @@ struct k3_ring_state {
  * @elm_size: Size of the ring element
  * @mode: Ring mode
  * @flags: flags
+ * @state: Ring state
  * @ring_id: Ring Id
  * @parent: Pointer on struct @k3_ringacc
  * @use_count: Use count for shared rings