egl/android: Partially handle HAL_PIXEL_FORMAT_IMPLEMENTATION_DEFINED

egl/android: Partially handle HAL_PIXEL_FORMAT_IMPLEMENTATION_DEFINED

There is no API available to properly query the IMPLEMENTATION_DEFINED
format. As a workaround we rely here on gralloc allocating either
an arbitrary YCbCr 4:2:0 or RGBX_8888, with the latter being recognized
by lock_ycbcr failing.

Reviewed-on: https://chromium-review.googlesource.com/566793

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: Chad Versace <chadversary@chromium.org>
Signed-off-by: Robert Foss <robert.foss@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>