ALSA: docs: Update MIDI 2.0 documentation for UMP 1.1 enhancement

There have been a few enhancements for the new UMP 1.1 features.
Update the documentation accordingly.

Link: https://lore.kernel.org/r/20230612081054.17200-11-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>