Fix bConfigurationValue property retrieval

Configuration is a property of the USB device. At a given time
host will only activate a single configuration.

Tested:
Verified on BMC that Configuration property is set correctly

Google-Bug-Id: 445480979
Change-Id: Ic2de0dd5dfcf4abc67793772a392ba36bb70dfb9
Signed-off-by: Kasun Athukorala <kasunath@google.com>