be2net: Fix endian issue in RX filter command

Use cpu_to_le32() for mcast_num field in RX filter command as this
field is of type u32.

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