iio: adc: ad7192: Use sysfs_emit_at

Replace scnprintf with sysfs_emit_at which is the preferred alternative.

Also make sure each fractional digit is in its place by padding with
zeros up to 3 digits: "...%03d...".
Signed-off-by: Alisa Roman <alisa.roman@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20230620163135.93780-1-alisa.roman@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7192.c

@@ -561,9 +561,8 @@ static ssize_t ad7192_show_filter_avail(struct device *dev,
 	ad7192_get_available_filter_freq(st, freq_avail);
 
 	for (i = 0; i < ARRAY_SIZE(freq_avail); i++)
-		len += scnprintf(buf + len, PAGE_SIZE - len,
-				 "%d.%d ", freq_avail[i] / 1000,
-				 freq_avail[i] % 1000);
+		len += sysfs_emit_at(buf, len, "%d.%03d ", freq_avail[i] / 1000,
+				     freq_avail[i] % 1000);
 
 	buf[len - 1] = '\n';