Add timeout to usb_device_get_string_ucs2 invocation to prevent potential

unbounded stuck state.

Consistent with other usages of usb_device_get_string (that calls
usb_device_get_string_ucs2) employing 200ms timeout values.

Bug:   b/113581955
Test:  Built and tested the code path.
Change-Id: I9fd0305ed4f6bffae16fd08f83f57ccac6c72de1