panfrost: Be more honest about PIPE_CAPs

panfrost: Be more honest about PIPE_CAPs

A lot of the pan_screen.c code was cargoculted from other drivers. The
upshot is that we return true for a lot of PIPE_CAPs that we don't
actually support, resulting in us exposing way too many extensions that
we don't actually support. Be more careful.

Some CAPs we do need to fake to access higher dEQP versions (i.e. in
order to debug the features we're hiding behind the CAP). For these, we
hide the CAP behind a special PAN_MESA_DEBUG=deqp option to avoid
apps randomly using these in-development features.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>