staging: rtl8187se: Use ether_addr_copy function

Use ether_addr_copy instead of memcpy function for fast copy an
Ethernet address in ieee80211/ieee80211_wx.c

Fixes sparse warnings:
WARNING: Prefer ether_addr_copy() over memcpy() if the Ethernet addresses are __aligned(2)

Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>