Only try to attach if parent device actually exists. I used ugly "/dev/${parent}" instead of "${parentdev}", because "/dev/" prefix for devices listed in gbde_devices variable is optional.
Only try to attach if parent device actually exists.
I used ugly "/dev/${parent}" instead of "${parentdev}", because "/dev/"
prefix for devices listed in gbde_devices variable is optional.

Reported by:	Sean McNeil <sean@mcneil.com>

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase