hammerhead: add charging led support

Also introduces led priority handling for
battery vs notification vs attention
(copied from jf-common).

Requires the hammerhead kernel led
always on support patch.

Change-Id: I1a2f3aae457c6d7e4e3c3f9ca39cbe42d39c3bc2
hammerhead: Update cpufreq settings

 * QC is switching to interactive. We will too.

Change-Id: I1ea4bdc75108136aa4b96e91da1a661b0b5d2b07