drivers: cpufreq: Send a uevent when governor changes

 * Useful so userspace tools can reconfigure.

Change-Id: Ib423910b8b9ac791ebe81a75bf399f58272f64f2
cpufreq: enforce governor to stay in sync across CPU cores

This is a shameless port of work done by @elbermu along
with some small changes to clean up the code a bit.

This patch forces both CPU0 & CPU1 to stay on the same
policy governor.  Currently, CPU1 defaults to a seemingly
random governor (usually intellidemand) regardless of what
governor the user selects.

Change-Id: I448e452f2ce572309c5b9b405ae6f18d3de3d3a0
tenderloin: regenerate defconfig