Added VAEntrypointEncSliceLP for implementations to expose a low power/high performance variant of slice level encoding entrypoint.
Added VAEntrypointEncSliceLP for implementations to expose a low power/high performance variant of slice level encoding entrypoint.

halleyzhao/libva-fdo,android-ia/hardware_intel_libva,android-ia/hardware_intel_libva,halleyzhao/libva-fdo,android-ia/hardware_intel_libva,CyanogenMod/android_hardware_intel_libva,halleyzhao/libva-fdo,CyanogenMod/android_hardware_intel_libva,CyanogenMod/android_hardware_intel_libva