etnaviv: Track different pipe_screens based on the file descriptions
This is not fully correct since we should use a combination of gpu_fd and kms_fd but since we only have a single GPU that will do atm.
Further discussion at https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6610#note_624920
Closes: #5 (closed)
Edited by Sebastian Krzyszkowiak