Staging: rtl8188eu: Fix warning of prefer ether_addr_copy.

This patch fixes the warning of "Prefer ether_addr_copy() over memcpy()
if the Ethernet addresses are __aligned(2)" in file rtw_cmd.c. Pahole
shows that the addresses are 2-byte aligned.

Signed-off-by: Elena Oat <oat.elena@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>