Added gpio_enable_interrupt() to enable them. This ensures that a
module which handles GPIO interrupts doesn't get them until it's
ready.
Signed-off-by: Randall Spangler <rspangler@chromium.org>
BUG=chrome-os-partner:7456
TEST=toggle power button while rebooting; without this fix it triggers a hard fault.
Change-Id: I35d926053963a70dd9246ce46a4913603b2b2489