etherdevice: Use ether_addr_copy to copy an Ethernet address

Some systems can use the normally known u16 alignment of
Ethernet addresses to save some code/text bytes and cycles.

This does not change currently emitted code on x86 by gcc 4.8.

Change-Id: Ic9f5ea49e345bd332bf08e75cd9f4957434fd3f8
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Git-commit: 286ab723d4b83d37deb4017008ef1444a95cfb0d
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-testing.git


[hkadmany@codeaurora.org: trivial conflict fix for 3.14]
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>