This patch extends the UMP core code to support the legacy MIDI 1.0
rawmidi devices.  When the new kconfig CONFIG_SND_UMP_LEGACY_RAWMIDI
is set, the UMP core allows to attach an additional rawmidi device for
each UMP Endpoint.  The rawmidi device contains 16 substreams where
each substream corresponds to a UMP Group belonging to the EP.  The
device reads/writes the legacy MIDI 1.0 byte streams and translates
from/to UMP packets.

The legacy rawmidi devices are exclusive with the UMP rawmidi devices,
hence both of them can't be opened at the same time unless the UMP
rawmidi is opened in APPEND mode.
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-15-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>