base-files: generate config files with correct permissions

As touch creates files with permission 0644 use umask to create
config files with permission 0600 to be inline with INSTALL_CONF

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

package/base-files/files/bin/config_generate

@@ -426,6 +426,8 @@ generate_gpioswitch() {
 json_init
 json_load "$(cat ${CFG})"
 
+umask 077
+
 if [ ! -s /etc/config/network ]; then
 	touch /etc/config/network
 	generate_static_network