drm/i915/de: allow intel_display and drm_i915_private for de functions

drm/i915/de: allow intel_display and drm_i915_private for de functions

It would be too much noise to convert the intel_de_* functions from
using struct drm_i915_private to struct intel_display all at once. Add
generic wrappers using __to_intel_display() to accept both.

v2: Take the intel_dmc_wl_* changes into account

Cc: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1b0e8e7c732535e18c8498a2e18fe1e4c123e2f5.1713358679.git.jani.nikula@intel.com