drm/xe/display: Flush DMC wakelock release work on runtime suspend

drm/xe/display: Flush DMC wakelock release work on runtime suspend

We currently are not calling display runtime suspend functions when
D3cold is not allowed. Because of that, we end up not disabling dynamic
DC states (and do not go to DC9). With dynamic DC states enabled, we
will also have DMC wakelock enabled. Since we use a delayed work to
release the DMC wakelock, the work might get executed a little too late
(after the PCI device has been put to D3hot) and we get a timeout
warning ("DMC wakelock release timed out") because the MMIO for
releasing the wakelock will be invalid after that point.

To fix that, make sure we flush the release work at the end of
xe_display_pm_runtime_suspend_late(). We can do that unconditionally
because, if there is no pending work, that turns into a no-op.

Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241129164010.29887-4-gustavo.sousa@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>