drm/etnaviv: take current primitive into account when checking for hung GPU

Large draws can make the GPU appear to be stuck to the current hangcheck
logic as the FE address will not move until the draw is finished. However,
the FE has a debug register, which records the current primitive ID within
a draw. Using this debug register we can extend the timeout as long as the
draw progresses.

Reviewed-by: Christian Gmeiner <cgmeiner@igalia.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>