mesa: Add GL_RGBA + GL_UNSIGNED_INT_2_10_10_10_REV for OES read type.

mesa: Add GL_RGBA + GL_UNSIGNED_INT_2_10_10_10_REV for OES read type.

This format + type combo is good for BGRA1010102 framebuffers
for use with glReadPixels() under GLES, so add it for the
GL_IMPLEMENTATION_COLOR_READ_TYPE_OES query.

Allows successful testing of 10 bpc / depth 30 rendering with dEQP test
case dEQP-EGL.functional.wide_color.window_1010102_colorspace_default.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Marek Olšák <marek.olsak@amd.com>