Keypad: Wake up on POWER_KEY only

no_suspend flag covers all the keys, however we only need to listen to POWER_KEY
GPIO IRQ. Also drop the separate CONFIG_ACER_A1_GPIO_KEYPAD since that keypad is
physically soldered on the board and can't go away. Fixes #18.
Cleanup: Rename and move acer-specific vars to board_acer.h

hw_version -> acer_hw_version
lcm_id -> acer_lcm_id
Cleanup: Touchscreen: move auo_ts out of board.h

Rename auo_ts to auo_h353_ts, give auo_h353_ts its own header and proper GPIO
name.