reported by Red Hat code analyzer:

cifs-utils-7.1/resolve_host.c:188:3: uninit_use_in_call: Using
uninitialized value "*site_name" as argument to "%s" when calling
"snprintf".

Signed-off-by: Pavel Filipenský <pfilipensky@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>