HID: handle joysticks with large number of buttons

Current HID code doesn't properly handle HID joysticks which have
larger number of buttons than what fits into current range reserved
for BTN_JOYSTICK.

One such joystick reported to not work properly is Saitek X52 Pro
Flight System.

We can't extend the range to fit more buttons in, because of backwards
compatibility reasons.

Therefore this patch introduces a new BTN_TRIGGER_HAPPY range, and
uses these to map the buttons which are over BTN_JOYSTICK limit.

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> [for the input.h part]
Signed-off-by: Jiri Kosina <jkosina@suse.cz>