libstagefright: return proper color format on target basis.

 Video preferred Color format is different for different targets.
Add a method to choose the preferred format for each target.

Patchset 1: Add QCOM_HARDWARE ifdefs

Conflicts:

	media/libstagefright/ACodec.cpp

Change-Id: Iba28d5d6e2917792492b3b2e9d38396d468f3202