staging/ozwpan: coding style ether_addr_copy

This fixes the following issues detected by checkpatch.pl:

 WARNING: Prefer ether_addr_copy() over memcpy() if the Ethernet addresses are __aligned(2)
 #220: FILE: drivers/staging/ozwpan/ozcdev.c:220:
 +              memcpy(g_cdev.active_addr, addr, ETH_ALEN);

 WARNING: Prefer ether_addr_copy() over memcpy() if the Ethernet addresses are __aligned(2)
 #286: FILE: drivers/staging/ozwpan/ozcdev.c:286:
 +                      memcpy(addr, g_cdev.active_addr, ETH_ALEN);

 WARNING: Prefer ether_addr_copy() over memcpy() if the Ethernet addresses are __aligned(2)
 #176: FILE: drivers/staging/ozwpan/ozpd.c:176:
 +              memcpy(pd->mac_addr, mac_addr, ETH_ALEN);

Signed-off-by: Jerome Pinot <ngc891@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>