app/testpmd: fix incorrect port number check
app/testpmd: fix incorrect port number check

testpmd parameter "nb-port" mean the number of forwarding port.
It's incorrect to use function port_id_is_invalid to check number of ports.

Fixes: edab33b1c01d ("app/testpmd: support port hotplug")

Signed-off-by: Yong Liu <d89ea4150d91f674af88bbc382d184dd42ea906c@intel.com>
Acked-by: Thomas Monjalon <ee2fa8b2681c737f775687e475dcbf2028a412f1@6wind.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk