drm/panthor: Support GLB_REQ.STATE field for Mali-G1 GPUs

drm/panthor: Support GLB_REQ.STATE field for Mali-G1 GPUs

Add support for the GLB_REQ.STATE field introduced in CSF v4.1+, which
replaces the HALT bit to provide finer control over the MCU state. This
change implements basic handling for transitioning the MCU between
ACTIVE and HALT states on Mali-G1 GPUs.

The update introduces new helpers to issue the state change requests,
poll for MCU halt completion, and restore the MCU to an active state
after halting.

Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Karunika Choo <karunika.choo@arm.com>
Link: https://patch.msgid.link/20251125125548.3282320-7-karunika.choo@arm.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>