drm/imagination: Improve firmware power off for layout_mars config

drm/imagination: Improve firmware power off for layout_mars config

In layout_mars HW config, Firmware MCU moved from Sidekick to new Mars
domain so Firmware takes care of powering down Sidekick/Jones and SLC.
Skip checks for those from kernel and check idle bits for Firmware MCU
and system arbiter excluding SOCIF.

Signed-off-by: Brajesh Gupta <brajesh.gupta@imgtec.com>
Reviewed-by: Matt Coster <matt.coster@imgtec.com>
Link: https://patch.msgid.link/20260313-b4-staging-layout_mars_base-v2-1-9e3c251d278e@imgtec.com
Signed-off-by: Matt Coster <matt.coster@imgtec.com>