wil6210: Prefer ether_addr_copy() over memcpy()

Fix checkpatch warning:
WARNING: Prefer ether_addr_copy() over memcpy() if the
Ethernet addresses are __aligned(2)

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>