xfs: silence uninitialised f.file warning.

Uninitialised variable build warning introduced by 2903ff0 ("switch
simple cases of fget_light to fdget"), gcc is not smart enough to
work out that the variable is not used uninitialised, and the commit
removed the initialisation at declaration that the old variable had.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_ioctl.c

@@ -70,7 +70,7 @@ xfs_find_handle(
 	int			hsize;
 	xfs_handle_t		handle;
 	struct inode		*inode;
-	struct fd		f;
+	struct fd		f = {0};
 	struct path		path;
 	int			error;
 	struct xfs_inode	*ip;