--ping-device argument parsing is broken

With version 1.19 (and current main) the --ping_device command always fails because it is trying to convert the device name into a number:

> tango_admin --ping-device "sys/tg_test/1"                                                                                                                                           
The parameter's value (sys/tg_test/1) cannot be converted to a numerical value.
Illegal parameter provided. Please try again!

The above command should work, as per the output of --help:

 --ping-device <dev> [max_time (s)] Check if the device is running

This was broken in cb684692 (Change return value to match errno defs, 2023-05-31) where we accidentally changed from using argv[3] to argv[2] for the timeout.