drm/{i915, xe}/display: pass parent interface to display probe

drm/{i915, xe}/display: pass parent interface to display probe

Let's gradually start calling i915 and xe parent, or core, drivers from
display via function pointers passed at display probe.

Going forward, the struct intel_display_parent_interface is expected to
include const pointers to sub-structs by functionality, for example:

struct intel_display_rpm {
	struct ref_tracker *(*get)(struct drm_device *drm);
	/* ... */
};

struct intel_display_parent_interface {
	/* ... */
	const struct intel_display_rpm *rpm;
};

This is a baby step towards not building display as part of both i915
and xe drivers, but rather making it an independent driver interfacing
with the two.

v3: useless include additions dropped
v2: unrelated include removal dropped

Cc: Jouni Högander <jouni.hogander@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patch.msgid.link/20251030202836.1815680-2-jouni.hogander@intel.com