Camera: add TARGET_PROVIDES_CAMERA_HAL

This allows qcom devices (such as msm8960 devices) to use a different camera hal.

Change-Id: Ibd06c7bc1bac431002019c79e308d3698bce29ae
use standard qcom naming for msm7x27a variants

Change-Id: I6b1dc453b166139bfff1f3bbed8302ff61ac24d3