aplay: Limit VUMeter progress bar to 100 for negative as well

aplay: Limit VUMeter progress bar to 100 for negative as well

While the progress bar cannot be negative, GCC concludes that it can be
and assumes tmp can be written past the end. Fixes this GCC warning:

aplay.c:1747:18: warning: '%02d' directive writing between 2 and 11 bytes
 into a region of size 4 [-Wformat-overflow=]
 1747 |    sprintf(tmp, "%02d%%", maxperc[c]);

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>