xfs: remove unnecessary null checks

The functions xfs_blkdev_put() and xfs_qm_dqrele() test whether
their argument is NULL and then return immediately.  Thus the test
around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 9f622fe..95745be 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -796,8 +796,7 @@
  out_free_ddev_targ:
 	xfs_free_buftarg(mp, mp->m_ddev_targp);
  out_close_rtdev:
-	if (rtdev)
-		xfs_blkdev_put(rtdev);
+	xfs_blkdev_put(rtdev);
  out_close_logdev:
 	if (logdev && logdev != ddev)
 		xfs_blkdev_put(logdev);