drm/panthor: Simplify FW fast reset path

drm/panthor: Simplify FW fast reset path

Stop checking the FW halt_status as MCU_STATUS should be sufficient.
This should make the check for successful FW halt and subsequently
setting fast_reset to true more robust.

We should also clear GLB_REQ.GLB_HALT bit only on post-reset prior
to starting the FW and only if we're doing a fast reset, because
the slow reset will re-initialize all FW sections, including the
global interface.

Signed-off-by: Karunika Choo <karunika.choo@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/r/20241119135030.3352939-1-karunika.choo@arm.com
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>