add maintainer for network drop monitor kernel service

I was getting ribbed about this earlier, so I figured I'd make it
official.  Add myself as the maintainer of the drop monitor bits, so
people don't just gripe at Dave when it breaks (I'm sure it will never
break, but just in case :) ).

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>