PowerHAL: Only write to SAMPLING_RATE_ONDEMAND when using Ondemand

Prevents E/CM PowerHAL(  559): Error opening /sys/devices/system/cpu/cpufreq/ondemand/sampling_rate: No such file or directory

PS2: Limit log spam (ALOGW -> ALOGV)

Signed-off-by: bmc08gt <bmc08gt.teamb00sted@gmail.com>
Change-Id: I2591028676cf9eca4978f1d8a88bae2ad5815109
Merge branch 'cm-10.1' of github.com:CyanogenMod/android_device_samsung_qcom-common into CyanogenMod-cm-10.1

Conflicts:
	power/power.c