ALSA: hda: generic: Check potential mixer name string truncation

add_control_with_pfx() constructs a mixer name element with the fixed
size, and it got compile warnings with -Wformat-truncation.

Although the size overflow is very unlikely, let's have a sanity check
of the string size and returns the error if it really doesn't fit
instead of silent truncation.

Link: https://lore.kernel.org/r/20230915082802.28684-14-tiwai@suse.de


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