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

Signed-off-by: bmc08gt <bmc08gt.teamb00sted@gmail.com>
Change-Id: I186b9bddd9518315e6f24bbeef1d131b6223996e
qcom: disable 4 layer MDP Composition temportarily

	* 3 layer MDP composition was backported to help alleviate
	  flicker due to an underrun with 4 layer MDP composition.
	  Disable 4 layer and only allow the 3 layer for now.

Signed-off-by: bmc08gt <bmc08gt.teamb00sted@gmail.com>
power: Use macros instead of string literals.

Replace multiple instances of string literals with
macros so as to minimize the risk of typos.

	* Also fix up loggin for ondemand sysfs_write (ALOGW->ALOGV)

Signed-off-by: bmc08gt <bmc08gt.teamb00sted@gmail.com>
Change-Id: I852ad370c2e371bb66e754ecc92e60f38c501047