libusbhost: Add usb_device_set_configuration and usb_device_set_interface

usb_device_set_configuration is to support devices with multiple configurations
usb_device_set_interface supports switching between interfaces with alternate settings

Also moved zero string index checking to usb_device_get_string

Change-Id: I34610b25f135894a0cf752a33e5738d4314d7122