drm/xe/display: clean up compat i915_vgpu.h

There's a bunch of unnecessary stuff not needed by display code. Remove.

Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/e583679c00aae8fec78f988fa857cfc724a9fa2d.1712345787.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>