kernel: sound: add support for MIDI 2.0 and UMP

kernel: sound: add support for MIDI 2.0 and UMP

New Packages / build options:
* sound-midi2: enable MIDI 2.0 / UMP in ALSA MIDI
* sound-midi2-seq: enable MIDI 2.0 / UMP in ALSA sequencer
* sound-midi2-usb: enable USB MIDI 2.0 support
* sound-dynamic-minors: allow more than 8 MIDI devices
More info about ALSA MIDI 2.0:
 https://docs.kernel.org/6.12/sound/designs/midi-2.0.html
More info about MIDI 2.0:
 https://midi.org/midi-2-0

Signed-off-by: Florian Bomers <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20727
Signed-off-by: Christian Marangi <[email protected]>