pm8xxx-led: Add API to configure pm8xxx LEDs

Add pm8xxx_led_configure API. It takes LED Id, mode,
and maximum current to be set.
Moreover,
1) Convert current values to actual current level using
   appropriate LED current factor.
2) Check brightness values against acceptable
   limits.

Signed-off-by: Jay Chokshi <jchokshi@codeaurora.org>
2 files changed