ALSA: ump: Copy FB name string more safely

The UMP group names are referred as the corresponding sequencer port
names, hence they should be proper ASCII strings.  OTOH, the UMP group
names are composed from the UMP FB strings that are received from the
device; i.e. a device may give some bogus letters and we can't trust
them fully.

To assure that the group names consist of the proper ASCII strings,
replace the normal string copy and append operations with special ones
that strip the non-printable letters.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250110155943.31578-5-tiwai@suse.de