Fix color conversion from OMX_COLOR_FormatYUV420SemiPlanar

Use NV12ToABGR for OMX_COLOR_Format32BitRGBA8888, and
NV12ToARGB for OMX_COLOR_Format32bitBGRA8888. The naming
convention is reverse in libyuv and omx.

bug: 129908793

test: locally modify StagefrightMetadataRetriever to prefer hw
decoder and output in OMX_COLOR_FormatYUV420SemiPlanar format.
The following tests would fail without this patch and pass with
this patch:

CtsMediaTestCases --android.media.cts.HeifWriterTest#testInputSurface_Grid_Handler fail
CtsMediaTestCases --android.media.cts.HeifWriterTest#testInputSurface_Grid_NoHandler fail
CtsMediaTestCases --android.media.cts.HeifWriterTest#testInputSurface_NoGrid_Handler fail
CtsMediaTestCases --android.media.cts.HeifWriterTest#testInputSurface_NoGrid_NoHandler fail
CtsMediaTestCases --android.media.cts.MediaMetadataRetrieverTest#testGetImageAtIndex fail

(These tests fail because they use bitmap format of RGB, while others
use RGB565.)

Change-Id: I94feea2c29479e72d6111ee6a7ce44805b921e73