Staging: et131x: Fix warning of prefer ether_addr_copy() in et131x.c

This patch fixes the following checkpatch.pl warnings:
WARNING: "Prefer ether_addr_copy() over memcpy() if the Ethernet addresses are __aligned(2)".
I used pahole to see whether addresses are aligned.

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>