drm/i915/de: Implement register waits one way

drm/i915/de: Implement register waits one way

Currently we use a messy mix of intel_wait_for_register*()
and __intel_wait_for_register*() to implement various
register polling functions. Make the mess a bit more understandable
by always using the __intel_wait_for_register*() stuff.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20251110172756.2132-2-ville.syrjala@linux.intel.com
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>