bridge_driver: Don't define network if XML contains more IPv4 adreses.

bridge_driver: Don't define network if XML contains more IPv4 adreses.

Only one IPv4 DHCP definition is supported. Originally the code checked
for a multiple definition and returned an error, but the new domain
definition was already added to networks. This patch moves the check
before the newly defined network is added to active networks.

 *src/network/bridge_driver.c: networkDefine(): - move multiple IPv4
                                                  addresses check before
                                                  definition is used.