Fix USB traceback during testing when wrong size
Fix USB traceback during testing when wrong size

In the pyusb_basic host test check the length of control transfers
before comparing contents for equality.

andcor02/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,mbedmicro/mbed,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,mbedmicro/mbed,andcor02/mbed-os,andcor02/mbed-os,kjbracey-arm/mbed,andcor02/mbed-os,kjbracey-arm/mbed,mbedmicro/mbed,kjbracey-arm/mbed