dell-wmi: Ignore WMI event code 0xe045

>From Dell we know that WMI event code 0xe045 is for Num Lock key, but it is
unclear due to message in commit 0b3f6109

 ("dell-wmi: new driver for
hotkey control").

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Michał Kępień <kernel@kempniu.pl>
Tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reviewed-by: Michał Kępień <kernel@kempniu.pl>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Link: https://lkml.org/lkml/2015/7/7/830


Signed-off-by: Darren Hart <dvhart@linux.intel.com>