be2net: clear promiscuous bits in adapter->flags while disabling promiscuous mode

We should clear promiscuous bits in adapter->flags while disabling promiscuous
mode. Else we will not put interface back into VLAN promisc mode if the vlans
already added exceeds the maximum limit.

Signed-off-by: Kalesh AP <kalesh.purayil@emulex.com>
Signed-off-by: Somnath Kotur <somnath.kotur@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>