msm7x30-common: Import msm7x30 power HAL

Change-Id: I91cc1825e75acf3358e0501463ac8ed734cdd866
msm7x30-common: Add makefile guard

* Only include subdirectories for msm7x30 targets

Change-Id: If2d4f25d441490e7a702586ec6df4294f15b9e00