bnx2: Support secondary MAC addresses.

Add support for configuring secondary unicast addresses.  There
are 4 additional perfect match filters which can be used for
secondary unicast address support.

  *  Modified bnx2_set_mac_addr() to be more generic in handling
     the setting of the perfect match filters
  *  Changed bnx2_set_rx_mode() to handle the unicast dev_addr_list

Signed-off-by: Benjamin Li <benli@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>