app/testpmd: fix valid ports prints

app/testpmd: fix valid ports prints

There are several cases of an invalid port data access that causes the
printing of all the valid ports, for example, when the user asks to
receive a port information of an invalid port.

Wrongly, the port with id 0 is printed in all the above described
cases, regardless of its validity.

Print port 0 only if it is valid as done for the rest of the ports.

Fixes: af75078fece3 ("first public release")
Fixes: b6ea6408fbc7 ("ethdev: store numa_node per device")
Fixes: edab33b1c01d ("app/testpmd: support port hotplug")
Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@mellanox.com>