msm: rq_stats: Disable hotplug and stats by default

Userspace closed source mpdecision binary is nessecary for PowerHAL to work.
As it depends on rq_stats, let's at least disable hotplugging and stats
collection by default. /sys/devices/system/cpu/cpu0/rq-stats/hotplug_disable
is now writable, so hotplug can be reenabled.

Also, add some bits related to current cpu policy.

Conflicts:
	arch/arm/mach-msm/msm_rq_stats.c