poppy: Updating scancodes to be uint16_t

uint8_t is too restrictive for all scancodes.
For example, volume up/down are 16 bits.

BUG=chrome-os-partner:61275
BRANCH=None
TEST=reboot and see if keyboard commands still work.

Change-Id: Ic439b4a4cf076600421fd5a979456c729693b739
Signed-off-by: Shelley Chen <shchen@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/426900
Reviewed-by: Randall Spangler <rspangler@chromium.org>
1 file changed