Input: spitzkbd - fix suspend key handling

The spitz keyboard driver reports KEY_SUSPEND events but doesn't
register its use of this event in the keybit bitfield, breaking
input events for this key. This patch fixes that by registering
the key in the keybit bitfield.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>