Hello! I've been working on supporting the KGSL kernel mode driver in gallium/freedreno, and I've run into a bit of an issue with some dri/drm related code inside `gallium/frontends/dri`. The issue is basically that to check if the driver supports importing a dmabuf it will query the capability through libdrm. Unfortunately KGSL is not a drm kernel driver so this check fails. I had an idea to expose more information through `PIPE_CAP_DMABUF`  on whether drm needs to be queried. I'm not really sure if this is the best way to do and I'm hoping to get some feedback on whether this is a good idea or if there might be a better way to achieve my goal. The change for this code can be found here: 
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21570/diffs?commit_id=0bfbddfe2b5b92fc8a44f47f3f6703b9c0558481

The change basically works by returning an enum instead of just `0` or `1` where the values now correspond to `PIPE_DMABUF_NOSUPPORT` and `PIPE_DMABUF_DRM`. Doing it this way means other drivers don't need to change their code. I then add a new possible value `PIPE_DMABUF_SUPPORTED` that tells DRI the feature is supported and does not need to be queried from drm.