drm/imagination: Use callbacks for fw irq handling
This allows for more versatility in checking and clearing firmware
registers used for interrupt handling.
Reviewed-by: Frank Binns <frank.binns@imgtec.com>
Link: https://lore.kernel.org/r/20250410-sets-bxs-4-64-patch-v1-v6-12-eda620c5865f@imgtec.com
Signed-off-by: Matt Coster <matt.coster@imgtec.com>