drm/{i915, xe}/bo: move display bo calls to parent interface

drm/{i915, xe}/bo: move display bo calls to parent interface

Continue i915 and xe separation from display by moving the bo calls to
the display parent interface. Instead of adding all these functions to
intel_parent.[ch], reuse the now vacated intel_bo.[ch], and avoid mass
renames to calls of these functions. This is similar to
intel_display_rpm.[ch].

Make many of the hooks optional to avoid having to implement dummy
functions in xe. Indeed now we can remove many of the existing dummy
functions.

Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/7899eef2ccf0cd603df69099df065226a0df917b.1773238670.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>