drm/panfrost: Introduce JM contexts for manging job resources

drm/panfrost: Introduce JM contexts for manging job resources

A JM context describes user-requested priorities for the JM queues.

Context creation leads to the initialization of scheduling entities of
the same priority for all the device's job slots.

Until context creation and destruction are exposed to UM, all issued
jobs shall be bound to the default Panfrost file context, which has
medium priority.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20250917191859.500279-3-adrian.larumbe@collabora.com