drm/apple: Fix parse_string() memory leaks

Signed-off-by: Asahi Lina <lina@asahilina.net>

Author: hoshinolina

drivers/gpu/drm/apple/parser.c

@@ -243,6 +243,9 @@ static int parse_dimension(struct dcp_parse_ctx *handle, struct dimension *dim)
 		else
 			skip(it.handle);
 
+		if (!IS_ERR_OR_NULL(key))
+			kfree(key);
+
 		if (ret)
 			return ret;
 	}
@@ -298,6 +301,9 @@ static int parse_color_modes(struct dcp_parse_ctx *handle, s64 *preferred_id)
 			else
 				skip(it.handle);
 
+			if (!IS_ERR_OR_NULL(key))
+				kfree(key);
+
 			if (ret)
 				return ret;
 		}
@@ -381,6 +387,9 @@ static int parse_mode(struct dcp_parse_ctx *handle,
 		else
 			skip(it.handle);
 
+		if (!IS_ERR_OR_NULL(key))
+			kfree(key);
+
 		if (ret)
 			return ret;
 	}
@@ -511,6 +520,9 @@ int parse_display_attributes(struct dcp_parse_ctx *handle, int *width_mm,
 		else
 			skip(it.handle);
 
+		if (!IS_ERR_OR_NULL(key))
+			kfree(key);
+
 		if (ret)
 			return ret;
 	}