usb-dbg: Handled error for host selector position

Added error handling for host selector position
and enhancement.

Tested on Yosemitev2

Signed-off-by: Karthikeyan Pasupathi <pkarthikeyan1509@gmail.com>
Change-Id: Iac9414ccc282bd3e24b6434f0ae57dac586659a6
3 files changed