ethernet: aquantia: Try MAC address from device tree

Apple M1 Mac minis (2020) with 10GE NICs do not have MAC address in the
card, but instead need to obtain MAC addresses from the device tree. In
this case the hardware will report an invalid MAC.

Currently atlantic driver does not query the DT for MAC address and will
randomly assign a MAC if the NIC doesn't have a permanent MAC burnt in.
This patch causes the driver to perfer a valid MAC address from OF (if
present) over HW self-reported MAC and only fall back to a random MAC
address when neither of them is valid.

Signed-off-by: Tianhao Chai <cth451@gmail.com>
Reviewed-by: Igor Russkikh <irusskikh@marvell.com>
Reviewed-by: Hector Martin <marcan@marcan.st>
Signed-off-by: David S. Miller <davem@davemloft.net>