driver core: Delete an unnecessary check before the function call "put_device"

commit 5f0163a5ee9cc7c59751768bdfd94a73186debba upstream.

The put_device() function tests whether its argument is NULL and then
returns 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[wt: backported only to ease next patch as suggested by Jiri]

Change-Id: I6acfe64cf7a4bac5fc25619cf160983c1b54b5c5
Signed-off-by: Willy Tarreau <w@1wt.eu>