Flapjack: Use PWM mode of MT6370 to control LED brightness
Flapjack: Use PWM mode of MT6370 to control LED brightness

This patch makes EC use the PWM mode of MT6370 to control the brightness
of the LEDs. This makes the colors match the requirements.

Current is fixed at 4mA. Brightness is controlled by PWM duty only.

Signed-off-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>

BUG=b/130197491
BRANCH=none
TEST=Verify the colors (amber, off, red, white) match the description.

Change-Id: Iacce4cc75af9b278ef77dcb2ececaf67a7631143
Reviewed-on: https://chromium-review.googlesource.com/1572452
Commit-Ready: ChromeOS CL Exonerator Bot <fa429e5907f00867f797423aea74327bb02c91b6@appspot.gserviceaccount.com>
Tested-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec