ALSA: rawmidi: Don't embed device

This patch detaches the struct device from the snd_rawmidi object by
allocating via snd_device_alloc(), just like done for other devices.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Tested-by: Curtis Malainey <cujomalainey@chromium.org>
Link: https://lore.kernel.org/r/20230816160252.23396-6-tiwai@suse.de


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