bnxt_en: Move bnxt_approve_mac().

Move it before bnxt_update_vf_mac().  In the next patch, we need to call
bnxt_approve_mac() from bnxt_update_mac() under some conditions.  This
will avoid forward declaration.

Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>