9p: Fix a bunch of kerneldoc warnings shown up by W=1

Fix a bunch of kerneldoc warnings shown up by W=1 in the 9p filesystem:

 (1) Add/remove/fix kerneldoc parameters descriptions.

 (2) Move __add_fid() from between v9fs_fid_add() and its comment.

 (3) 9p's caches_show() doesn't really make sense as an API function, so
     remove the kerneldoc annotation.  It's also not prefixed with 'v9fs_'.
     Also remove the kerneldoc markers from the 9p fscache wrappers.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Dominique Martinet <asmadeus@codewreck.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Mauro Carvalho Chehab <mchehab@kernel.org>
cc: v9fs-developer@lists.sourceforge.net
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
diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index 9d9de62..b8863dd 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -19,18 +19,18 @@
 #include "v9fs_vfs.h"
 #include "fid.h"
 
+static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
+{
+	hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
+}
+
+
 /**
  * v9fs_fid_add - add a fid to a dentry
  * @dentry: dentry that the fid is being added to
  * @fid: fid to add
  *
  */
-
-static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
-{
-	hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
-}
-
 void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
 {
 	spin_lock(&dentry->d_lock);
@@ -67,7 +67,7 @@ static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid)
 
 /**
  * v9fs_open_fid_add - add an open fid to an inode
- * @dentry: inode that the fid is being added to
+ * @inode: inode that the fid is being added to
  * @fid: fid to add
  *
  */