nfs: Fix kerneldoc warning shown up by W=1

Fix a kerneldoc warning in nfs due to documentation for a parameter that
isn't present.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna.schumaker@netapp.com>
cc: Mauro Carvalho Chehab <mchehab@kernel.org>
cc: linux-nfs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/r/163214005516.2945267.7000234432243167892.stgit@warthog.procyon.org.uk/ # rfc v1
Link: https://lore.kernel.org/r/163281899704.2790286.9177774252843775348.stgit@warthog.procyon.org.uk/ # rfc v2

fs/nfs_common/grace.c

@@ -42,7 +42,6 @@ EXPORT_SYMBOL_GPL(locks_start_grace);
 
 /**
  * locks_end_grace
- * @net: net namespace that this lock manager belongs to
  * @lm: who this grace period is for
  *
  * Call this function to state that the given lock manager is ready to