cpufreq: Typecast compared integers

The min/max frequencies in cpufreq_policy are unsigned integers
but pm_qos_request() returns a signed int. Compare as unsigned,
frequencies are never negative.

Bug 949219

Change-Id: Iba0de9ad6bf221f7a2e5560f597aa56cbeb7b6f6
Signed-off-by: Antti P Miettinen <amiettinen@nvidia.com>
Reviewed-on: http://git-master/r/91214
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: Juha Tukkinen <jtukkinen@nvidia.com>

Rebase-Id: Rf996a487f263e4bee451da38d3317a6ae53214dd

Conflicts:
	drivers/cpufreq/cpufreq.c