bridge: vni: Remove stray newlines after each interface

bridge: vni: Remove stray newlines after each interface

Currently, `bridge vni` outputs an empty line after each interface. This is
not consistent with the output style of other iproute2 commands, in
particular `bridge vlan`. Therefore, remove the empty lines.

If there are scripts that parse the normal text output of `bridge vni`,
those scripts might be broken by the removal of the empty lines. This is a
secondary concern because those scripts should consume the JSON output
instead.

Before:
$ bridge vni
dev               vni              group/remote
vxlan1             4001
                   5000-5010

vxlan2             100

$

After:
$ ./bridge/bridge vni
dev               vni              group/remote
vxlan1             4001
                   5000-5010
vxlan2             100
$

Reviewed-by: Petr Machata <petrm@nvidia.com>
Tested-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>