block/gluster: fix port type in the QAPI options list

After introduction of qapi schema in gluster block driver code, the port
type is now string as per InetSocketAddress

{ 'struct': 'InetSocketAddress',
  'data': {
    'host': 'str',
    'port': 'str',
    '*to': 'uint16',
    '*ipv4': 'bool',
    '*ipv6': 'bool' } }

but the current code still treats it as QEMU_OPT_NUMBER, hence fixing port
to accept QEMU_OPT_STRING.
Suggested-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NPrasanna Kumar Kalever <prasanna.kalever@redhat.com>
Reviewed-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

block/gluster.c

@@ -186,7 +186,7 @@ static QemuOptsList runtime_tcp_opts = {
         },
         {
             .name = GLUSTER_OPT_PORT,
-            .type = QEMU_OPT_NUMBER,
+            .type = QEMU_OPT_STRING,
             .help = "port number on which glusterd is listening (default 24007)",
         },
         {