9p: rename uid and gid parameters

Change the names of 'uid' and 'gid' parameters to the more appropriate
'dfltuid' and 'dfltgid'.  This also sets the default uid/gid to -2
(aka nfsnobody)

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 2270d06..f08a35d 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -805,8 +805,8 @@
 	inode->i_mtime.tv_sec = stat->mtime;
 	inode->i_ctime.tv_sec = stat->mtime;
 
-	inode->i_uid = v9ses->uid;
-	inode->i_gid = v9ses->gid;
+	inode->i_uid = v9ses->dfltuid;
+	inode->i_gid = v9ses->dfltgid;
 
 	if (v9fs_extended(v9ses)) {
 		inode->i_uid = stat->n_uid;