HID: hid-debug: more informative output for EV_KEY

Currently hid-debug's hid_resolv_event prints questions marks for
all entries without explicit mapping information. This makes
debugging unnecessarily complicated as multiple different
keys may simply result in the same uninformative output.

Some common event codes are deliberately not defined in
input-event-codes.h. For example the 16th gamepad key.

Instead, print the hexadecimal codes for all events without symbolic
names.

Signed-off-by: Thomas Kuehne <thomas.kuehne@gmx.li>
Signed-off-by: Jiri Kosina <jkosina@suse.com>