staging: rtl8192e: Make ethernet addresses properly aligned

Reorder ethernet addresses allocated on stack or in non-packed
structures to keep them aligned(2).
Use ETH_ALEN as array length in places where it was hardcoded to 6.

Alignment verified using pahole where possible and target-tested
with BUG_ON() trap in ether_addr_copy.

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