panfrost: Ensure we have ro before using it

panfrost: Ensure we have ro before using it

Even through the resouce requested has a BIND_SCANOUT or related tag,
this does not mean that we have a render-only driver.

This can trivially happen as one requests such resource from GBM, while
using the panfrost fd (and hence panfrost_dri.so)

Forward port of !3000

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Robert Foss <robert.foss@collabora.com>
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Closes: #2664
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5410>