drm/i915/display: move enum aux_ch to intel_display_limits.h

drm/i915/display: move enum aux_ch to intel_display_limits.h

Move enum aux_ch from intel_display.h to intel_display_limits.h to avoid
having to include the former from gvt. This currently happens via
intel_display_types.h, which we can also drop in favour of
intel_display_limits.h in intel_gvt_mmio_table.c.

Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/86ccc91ee1ca96fa145b750e2f1935918ec288d0.1769612208.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>