Fix runtime error when add `additional-ports` configuration

The bmcweb has runtime errors when adding `additional-ports`
configuration.

```text
Dec 19 21:25:54 board systemd[1]: sockets.target: Wants dependency dropin /etc/systemd/system/sockets.target.wants/bmcweb_440 is not a valid unit name, ignoring.
```

and

```text
Dec 19 21:25:54 board systemd[1]: bmcweb_440.socket: Unit has no Listen setting (ListenStream=, ListenDatagram=, ListenFIFO=, ...). Refusing.
Dec 19 21:25:54 board systemd[1]: bmcweb_440.socket: Cannot add dependency job, ignoring: Unit bmcweb_440.socket has a bad unit file setting.
```

Update the code to fix that.

Change-Id: I792b9fdf29df40137fdbc7418b140e8445080961
Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
diff --git a/config/meson.build b/config/meson.build
index d4c4499..eb29cf6 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -153,7 +153,7 @@
         auth = auths[index]
     endif
 
-    filename = 'bmcweb_' + port_number
+    filename = 'bmcweb_' + port_number + '.socket'
     configure_file(
         input: 'bmcweb.socket.in',
         output: filename,
@@ -161,7 +161,7 @@
         install: true,
         configuration: configuration_data(
             {
-                'BMCWEB_HTTPS_PORT': port_number,
+                'BMCWEB_PORT': port_number,
                 'HTTP_LEVEL_ALLOWED': 'https',
                 'HTTP_BIND': bind_to_device,
                 'HTTP_AUTH_LEVEL': auth,