drm/i915/bios: add DP max link rate to VBT child device struct

Update VBT defs to reflect revision 216. While at it, default the
expected child device struct size to sizeof the size rather than a
hardcoded value.

v2: Fix bit order (David)

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180118153310.32437-1-jani.nikula@intel.com

drivers/gpu/drm/i915/intel_bios.c

@@ -1323,11 +1323,13 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
 		expected_size = LEGACY_CHILD_DEVICE_CONFIG_SIZE;
 	} else if (bdb->version == 195) {
 		expected_size = 37;
-	} else if (bdb->version <= 197) {
+	} else if (bdb->version <= 215) {
 		expected_size = 38;
+	} else if (bdb->version <= 216) {
+		expected_size = 39;
 	} else {
-		expected_size = 38;
-		BUILD_BUG_ON(sizeof(*child) < 38);
+		expected_size = sizeof(*child);
+		BUILD_BUG_ON(sizeof(*child) < 39);
 		DRM_DEBUG_DRIVER("Expected child device config size for VBT version %u not known; assuming %u\n",
 				 bdb->version, expected_size);
 	}

drivers/gpu/drm/i915/intel_vbt_defs.h

@@ -412,6 +412,8 @@ struct child_device_config {
 	u16 dp_gpio_pin_num;					/* 195 */
 	u8 dp_iboost_level:4;					/* 196 */
 	u8 hdmi_iboost_level:4;					/* 196 */
+	u8 dp_max_link_rate:2;					/* 216 CNL+ */
+	u8 dp_max_link_rate_reserved:6;				/* 216 */
 } __packed;
 
 struct bdb_general_definitions {