HID: Fix debug name for BTN_GEAR_DOWN, BTN_GEAR_UP, BTN_WHEEL

The name of BTN_GEAR_DOWN was WheelBtn and BTN_WHEEL was missing. Further,
BTN_GEAR_UP had a space in its name and no Btn, which is against convention.
This makes the names BtnGearDown, BtnGearUp, and BtnWheel, fixing the errors
and matching convention.

Signed-off-by: Vicki Pfau <vi@endrift.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>