Staging: rtl8188eu: Fix warning of prefer ether_addr_copy().

This patch fixes the warning produced by checkpatch "Prefer
ether_addr_copy() over memcpy() if the Ethernet addresses are
__aligned(2)". The address that is copied is a field of
nat25_network_db_entry structure. Definition for this struct is found in
rtw_br_ext.h file. 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>