drm/i915/dmc_wl: Add and use HAS_DMC_WAKELOCK()

drm/i915/dmc_wl: Add and use HAS_DMC_WAKELOCK()

A HAS_DMC_WAKELOCK() macro gives more semantic than openly checking the
display version. Define it and use it where appropriate.

v2:
  - Make this patch contain only the non-functional refactor. Functional
    changes related to including HAS_DMC() in the macro are done in
    upcoming changes. (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241108130218.24125-14-gustavo.sousa@intel.com