keyboard: adding functional alt/shift lights

This is useful for devices that has QWERTY keyboard
and leds for the Alt/Shift (Fn/Caps) keys, like
htc doubleshot.

Depends on libhardware patch for the light ids:
http://review.cyanogenmod.org/34902

Change-Id: I66ebc2d881438f5b51db77eaa885421e65a7da0d