cpufreq: Enforce PM QoS min/max limits

Observe PM QoS CPU frequency minimum and maximum in addition
to policy settings.

Bug 888312

Change-Id: Ia4f60a1649a9952e02f6847c8add3b2ea5d47524
Reviewed-on: http://git-master/r/72207
Signed-off-by: Antti P Miettinen <amiettinen@nvidia.com>
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Reviewed-on: http://git-master/r/75884
Reviewed-by: Automatic_Commit_Validation_User

Rebase-Id: Red1299253123d231af705a130f07e7aa77698fd8

Conflicts:
	drivers/cpufreq/cpufreq.c