st/mesa: Also check for PIPE_FORMAT_A8R8G8B8_SRGB for texture_sRGB

st/mesa: Also check for PIPE_FORMAT_A8R8G8B8_SRGB for texture_sRGB

and PIPE_FORMAT_R8G8B8A8_SRGB, as well.

The reason for this is that when Virgl runs with GLES on the host, it
cannot directly upload textures in BGRA.

So to avoid a conversion step, consider the RGB sRGB formats as well for
this extension.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>