Allow to setup custom device in Terminal example

Terminal example allows to select only available devices which are
received from QSPI. Now it is possible to enter and to open of any
custom device.

Change-Id: I83172a346cb5dc0e20c217957133e9e3e506d8a4
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>