bridge: Fix tunnelshow json output

bridge: Fix tunnelshow json output

repeats for "vlan tunnelshow" what commit 0f36267485e3 ("bridge: fix vlan
show formatting") did for "vlan show". This fixes problems in json output.

Note that the resulting json output format of "vlan tunnelshow" is not the
same as the original, introduced in commit 8652eeb3ab12 ("bridge: vlan:
support for per vlan tunnel info"). Changes similar to the ones done for
"vlan show" in commit 0f36267485e3 ("bridge: fix vlan show formatting") are
carried over to "vlan tunnelshow".

Fixes: c7c1a1ef51ae ("bridge: colorize output and use JSON print library")
Fixes: 0f36267485e3 ("bridge: fix vlan show formatting")
Signed-off-by: Benjamin Poirier <bpoirier@cumulusnetworks.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>