ALSA: ump: Fix -Wformat-truncation warnings

Filling the rawmidi name and substream name can be truncated, and this
leads to spurious compiler warnings due to -Wformat-truncation.
Although the truncation is the expected behavior, it'd be better to
truncate the string within "(...)"

This patch puts the precision specifies to each %s for fitting the
words within the size-limited strings.

Fixes: 5f11dd93 ("ALSA: usb-audio: Attach legacy rawmidi after probing all UMP EPs")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202308251844.1FuQYsql-lkp@intel.com/
Link: https://lore.kernel.org/r/20230826072151.23408-1-tiwai@suse.de


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