drm: rcar-du: Add group hooks for atomic-commit

The group can now be handled independently from the CRTC tracking its
own state.

Introduce an rcar_du_group_atomic_check() call which will iterate the
CRTCs to determine the per-state use-count of the group.

This use count then allows us to determine if the group should be
configured or disabled in our commit tail through the introduction of
two new calls rcar_du_group_atomic_{pre,post}_commit().

The existing rcar_du_group_{get,put}() functions are now redundant and
removed along with their interactions in the CRTC get/put calls.

The groups share clocking with the CRTCs within the group, and so are
accessible only when one of its CRTCs has been powered through

Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
4 files changed