Staging: vt6656: incorporated ETH_ALEN macro instead of custom one

Replaced custom U_ETHER_ADDR_LEN by ETH_ALEN from <linux/if_ether.h>.
Resolved checkpatch findings on the changed lines, mostly indentation.

Signed-off-by: Andres More <more.andres@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>