samples: subsys: usb: midi: demonstrate usage of UMP Stream responder

Update the USB-MIDI2.0 sample to use the newly introduced
UMP Stream Responder library. This allows the host to discover the
topology and function block names (if supported by the host OS).

Signed-off-by: Titouan Christophe <titouan.christophe@mind.be>
3 files changed