license: add missing SPDX headers

Add SPDX header to files with existing license.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

subsys/net/lib/http/http_parser_url.c

@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: MIT */
+
 /* Based on src/http/ngx_http_parse.c from NGINX copyright Igor Sysoev
  *
  * Additional changes are licensed under the same terms as NGINX and