drm/i915/lnl: Add gmbus/ddc support

LNL's south display uses the same table as MTP. Check for LNL's fake PCH
to make it consistent with the other checks.

The VBT table doesn't contain the VBT -> spec mapping for LNL. Like in
other cases, uses the same as the previous platform.

Bspec: 68971, 20124
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919192128.2045154-18-lucas.demarchi@intel.com

drivers/gpu/drm/i915/display/intel_bios.c

@@ -2194,7 +2194,8 @@ static u8 map_ddc_pin(struct drm_i915_private *i915, u8 vbt_pin)
 	const u8 *ddc_pin_map;
 	int i, n_entries;
 
-	if (HAS_PCH_MTP(i915) || IS_ALDERLAKE_P(i915)) {
+	if (INTEL_PCH_TYPE(i915) >= PCH_LNL || HAS_PCH_MTP(i915) ||
+	    IS_ALDERLAKE_P(i915)) {
 		ddc_pin_map = adlp_ddc_pin_map;
 		n_entries = ARRAY_SIZE(adlp_ddc_pin_map);
 	} else if (IS_ALDERLAKE_S(i915)) {

drivers/gpu/drm/i915/display/intel_gmbus.c

@@ -155,7 +155,10 @@ static const struct gmbus_pin *get_gmbus_pin(struct drm_i915_private *i915,
 	const struct gmbus_pin *pins;
 	size_t size;
 
-	if (INTEL_PCH_TYPE(i915) >= PCH_DG2) {
+	if (INTEL_PCH_TYPE(i915) >= PCH_LNL) {
+		pins = gmbus_pins_mtp;
+		size = ARRAY_SIZE(gmbus_pins_mtp);
+	} else if (INTEL_PCH_TYPE(i915) >= PCH_DG2) {
 		pins = gmbus_pins_dg2;
 		size = ARRAY_SIZE(gmbus_pins_dg2);
 	} else if (INTEL_PCH_TYPE(i915) >= PCH_DG1) {