ALSA: oxygen: configure MIDI via device_config

To enable the MIDI port, model drivers must now set flags in
device_config, not only in misc_flags.  This allows model drivers to
enable the UART without creating an ALSA MIDI device.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
diff --git a/sound/pci/oxygen/oxygen.c b/sound/pci/oxygen/oxygen.c
index bb2e7d8..62888c7 100644
--- a/sound/pci/oxygen/oxygen.c
+++ b/sound/pci/oxygen/oxygen.c
@@ -297,6 +297,7 @@
 					    CAPTURE_0_FROM_I2S_2 |
 					    CAPTURE_1_FROM_SPDIF;
 		chip->model.misc_flags = OXYGEN_MISC_MIDI;
+		chip->model.device_config |= MIDI_OUTPUT | MIDI_INPUT;
 	}
 	return 0;
 }