drm/{i915, xe}: Remove i915_reg.h from g4x_hdmi.c
Move TRANS_CHICKEN1 reg to display header to make g4x_hdmi.c
free from i915_reg.h dependency.
v2: Remove from common header in include and use display_regs.h (Jani)
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patch.msgid.link/20260205094341.1882816-14-uma.shankar@intel.com