cpufreq: ondemand: Disable freq sync feature in store_powersave_bias

Turn off frequency synchronization of CPUs on thread migrations
when powersave bias is enabled. This is done to prevent re-arming
of the dbs timer work (which is cancelled by store_powersave_bias)
by the sync_thread.

Change-Id: I165dd591845c1d66d01a14e8dfc44c767c677b0d
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>

Conflicts:
	drivers/cpufreq/cpufreq_ondemand.c
cpufreq: ondemand: fix timer-related list corruption in store_powersave_bias()

The dbs_timer_init() call in store_powersave_bias() re-initializes the
dbs_info workqueue, call on dbs_timer_exit() to ensure
outstanding work is cleared prior to making this call. Also, grab the
percpu timer_mutex lock to avoid race conditions with respect to the
dbs timer.

Change-Id: I79f3d43eeb51d2d8e21edd0fe043d6583333951f
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>