This drives the power LED for Snow (PB3) using TIM2 in PWM mode.
Since timer setup and manipulation is STM32-specific, the power LED
logic moved to to chip/stm32/power_led.c.
This also adds a "powerled" console command for testing.
Signed-off-by: David Hendricks <dhendrix@chromium.org>
BUG=chrome-os-partner:10647
TEST=Tested on Snow with powerled command, compiled for Daisy
Change-Id: I5a7dc20d201ea058767e3e76d54e7c8567a3b83c
Reviewed-on: https://gerrit.chromium.org/gerrit/26267
Commit-Ready: David Hendricks <dhendrix@chromium.org>
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Tested-by: David Hendricks <dhendrix@chromium.org>