tools: PCI: Add a missing option help line

Add a missing option help line for performing legacy interrupt test.

Signed-off-by: Stan Drozd <drozdziak1@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
1 file changed