HID: picoLCD: fix a NULL test in picolcd_raw_cir()

Smatch complains that the NULL checking in this function is not
consistent and could lead to a NULL dereference.  The comments say that
we should return here if rc_dev is NULL so I've changed the test to
match the comment.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>