NFSv4.1: Simplify setting the layout header credential

ctx->cred == ctx->state->owner->so_cred, so let's just use the former.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pnfs.c

@@ -1052,7 +1052,7 @@ alloc_init_layout_hdr(struct inode *ino,
 	INIT_LIST_HEAD(&lo->plh_segs);
 	INIT_LIST_HEAD(&lo->plh_bulk_destroy);
 	lo->plh_inode = ino;
-	lo->plh_lc_cred = get_rpccred(ctx->state->owner->so_cred);
+	lo->plh_lc_cred = get_rpccred(ctx->cred);
 	return lo;
 }