staging: rtl8192e: Fix PREFER_ETHER_ADDR_COPY warnings

Replace memcpy() with ether_addr_copy() where possible to make
checkpatch.pl happy.
Change was target tested (download 1Mb file over WPA2 network)
with BUG trap for unaligned addresses in ether_addr_copy()

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>