openvswitch: meter: Fix setting meter id for new entries

The meter code would create an entry for each new meter.  However, it
would not set the meter id in the new entry, so every meter would appear
to have a meter id of zero.  This commit properly sets the meter id when
adding the entry.

Fixes: 96fbc13d ("openvswitch: Add meter infrastructure")
Signed-off-by: Justin Pettit <jpettit@ovn.org>
Cc: Andy Zhou <azhou@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>