ath10k: prefer ether_addr_copy() over memcpy()

Fixes checkpatch warning:

drivers/net/wireless/ath/ath10k/wmi.c:5800: Prefer ether_addr_copy() over memcpy() if the Ethernet addresses are __aligned(2)

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>