The Linux kernel, from which checkpatch originates, contains function
ether_addr_copy() to copy Ethernet MAC addresses, and checkpatch warns
that it should be used in preference to memcpy() where appropriate.
U-Boot doesn't contain ether_addr_copy(), so tell checkpatch not to issue
this warning.

Signed-off-by: Stephen Warren <[email protected]>
Reviewed-by: Marek Vasut <[email protected]>
Acked-by: Joe Hershberger <[email protected]>
Tested-by: Anand Moon <[email protected]>
Reviewed-by: Anand Moon <[email protected]>