drm/i915/dmc_wl: Extract intel_dmc_wl_flush_release_work()

We will need to flush the release work from outside in an upcoming
change. Let's put that into a public interface and call it
intel_dmc_wl_flush_release_work().

Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241129164010.29887-2-gustavo.sousa@intel.com


Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>