Avoid to use strncpy and do proper length limiting (12 bytes)
to avoid out of array access.

Fixes: d712c58c ("ALSA: pcm: optimize and clarify stream synchronization ID API")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407050501.o5Z3bibi-lkp@intel.com/Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Link: https://patch.msgid.link/20240705075828.19746-1-perex@perex.czSigned-off-by: Takashi Iwai <tiwai@suse.de>