Fix the following gcc warning:

drivers/input/serio/apbps2.c:106:16: warning: variable ‘tmp’ set but not
used [-Wunused-but-set-variable].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/1617958859-64707-1-git-send-email-jiapeng.chong@linux.alibaba.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>