staging: rtl8723bs: use ether_addr_copy() in rtw_macaddr_cfg()

Use ether_addr_copy() instead of memcpy() to copy the mac address.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>