be2net: Fix disabling multicast promiscous mode

If user tries to disable multicast promiscous mode, the adapter remains
in this mode as resetting the multicast promiscous mode was missing
in RX filter command. Fixed this.

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>