nfp: add missing kdoc

Add missing kdoc for app member.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/ccm.h

@@ -54,6 +54,8 @@ static inline unsigned int nfp_ccm_get_tag(struct sk_buff *skb)
 
 /**
  * struct nfp_ccm - common control message handling
+ * @app:		APP handle
+ *
  * @tag_allocator:	bitmap of control message tags in use
  * @tag_alloc_next:	next tag bit to allocate
  * @tag_alloc_last:	next tag bit to be freed