ethernet: manually convert memcpy(dev_addr,..., sizeof(addr))

A handful of drivers use sizeof(addr) for the size of
the address, after manually confirming the size is
indeed 6 convert them to eth_hw_addr_set().

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Petko Manolov <petkan@nucleusys.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>