drm/i915/bios: Define the (obsolete) backlight i2c VBT stuff

The VBT backlight entries include various fields for i2c
controlled backlights. These have been obsoleted at some
unknown point in time, but let's define them anyway so that
we have a full picture of what has been in there.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240321161806.31714-5-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_vbt_defs.h

@@ -881,11 +881,12 @@ struct bdb_lvds_lfp_data_tail {
 struct lfp_backlight_data_entry {
 	u8 type:2;
 	u8 active_low_pwm:1;
-	u8 obsolete1:5;
+	u8 i2c_pin:3;						/* obsolete since ? */
+	u8 i2c_speed:2;						/* obsolete since ? */
 	u16 pwm_freq_hz;
 	u8 min_brightness;					/* ???-233 */
-	u8 obsolete2;
-	u8 obsolete3;
+	u8 i2c_address;						/* obsolete since ? */
+	u8 i2c_command;						/* obsolete since ? */
 } __packed;
 
 struct lfp_backlight_control_method {