net/core: dev_mc_sync_multiple calls wrong helper

The dev_mc_sync_multiple function is currently calling
__hw_addr_sync, and not __hw_addr_sync_multiple.  This will result in
addresses only being synced to the first device from the set.

	Corrected by calling the _multiple variant.

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Reviewed-by: Vlad Yasevich <vyasevic@redhat.com>
Tested-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: David S. Miller <davem@davemloft.net>