egl: Fix A2RGB10 platform_{device,surfaceless} PBuffer configs.
Since some time egl_ext_device_base fails on hardware devices. The proposed change fixes that with a point fix.
The _DRI_IMAGE_FORMAT* part wants to be handled for the *101010 type formats as well. Assert on an unknown format so that a failure there gets detected earlier. That again makes the piglit egl_ext_device_base test work again for hardware drivers.
Fixes: 9acb94b6 "egl: Enable 10bpc EGLConfigs for platform_{device,surfaceless}" Signed-off-by: Mathias Fröhlich Mathias.Froehlich@web.de