Staging: hv: use existing Ethernet header size

Use ETH_ALEN to indicate that MAC address is Ethernet.
Also use Linux printk format for mac addresses.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>