minnowboard-keys: Bind MinnowBoard buttons to arrow keys

Configure the four buttons tied to the E6XX GPIO lines on the
MinnowBoard as keys using the gpio-keys-polled platform driver. From
left to right, bind them to LEFT, DOWN, UP, RIGHT, similar to the VI
directional keys.

This is separate from the minnowboard driver to provide users with the
flexibility to write kernel drivers for their own devices using these GPIO
lines.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
3 files changed