bnxt_en: Fixed incorrect implementation of ndo_set_mac_address

The existing ndo_set_mac_address only copies the new MAC addr
and didn't set the new MAC addr to the HW. The correct way is
to delete the existing default MAC filter from HW and add
the new one. Because of RFS filters are also dependent on the
default mac filter l2 context, the driver must go thru
close_nic() to delete the default MAC and RFS filters, then
open_nic() to set the default MAC address to HW.

Signed-off-by: Jeffrey Huang <huangjw@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>