feat: add MIDI 2.0 Host class driver (USB-MIDI 2.0)

Add native USB-MIDI 2.0 Host class driver to TinyUSB. Implements
reactive architecture: enumerate, detect MIDI 2.0 capability, inform
application via callbacks.

Driver features:
- Parse both Alt Setting 0 (MIDI 1.0) and Alt Setting 1 (UMP)
- Detect bcdMSC version from descriptor
- Auto-select highest protocol (Alt 1 preferred if available)
- UMP read/write via endpoint streams
- Proper Audio Control interface skip (loop-based, following
  midi_host.c pattern)
- Endpoint open with tuh_edpt_open/tu_edpt_stream_open/clear
- usbh_driver_set_config_complete for USBH state machine
- Handle Audio Control itf_num in set_config gracefully
- 5 weak callback stubs (descriptor, mount, unmount, rx, tx)

Build system:
- Register midih2_* in usbh.c driver table
- Add midi2_host.h include to tusb.h
- Add CFG_TUH_MIDI2_LOG_LEVEL to tusb_option.h

All changes guarded by #if CFG_TUH_MIDI2 (default 0). Zero impact on
existing drivers and examples.

Tested: Waveshare RP2350-USB-A (Host) receiving UMP from Raspberry Pi
Pico (Device) via PIO-USB, board-to-board

1 files changed, 12 insertions, 0 deletions

diff --git a/src/host/usbh.c b/src/host/usbh.c
index 490724b02..2e3c93c5e 100644
--- a/src/host/usbh.c
+++ b/src/host/usbh.c
@@ -278,6 +278,18 @@ static usbh_class_driver_t const usbh_class_drivers[] = {
   },
   #endif
 
+  #if CFG_TUH_MIDI2
+  {
+      .name       = DRIVER_NAME("MIDI2"),
+      .init       = midih2_init,
+      .deinit     = midih2_deinit,
+      .open       = midih2_open,
+      .set_config = midih2_set_config,
+      .xfer_cb    = midih2_xfer_cb,
+      .close      = midih2_close
+  },
+  #endif
+
   #if CFG_TUH_HUB
   {
       .name       = DRIVER_NAME("HUB"),