drm/i915: Expect child dev size of 22 bytes for VBT < 106

My 830 has VBT version 105 with child device size of 22 bytes.
Let's assume that's correct and adjust our expectations.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450110229-30450-9-git-send-email-ville.syrjala@linux.intel.comAcked-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_bios.c

@@ -1157,7 +1157,9 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
 		DRM_DEBUG_KMS("No general definition block is found, no devices defined.\n");
 		return;
 	}
-	if (bdb->version < 109) {
+	if (bdb->version < 106) {
+		expected_size = 22;
+	} else if (bdb->version < 109) {
 		expected_size = 27;
 	} else if (bdb->version < 195) {
 		BUILD_BUG_ON(sizeof(struct old_child_dev_config) != 33);