Do not truncate stderr file output

Another script would use sxmo_modemsendsms and maybe put its error
somewhere. We should not truncate stderr as it would break those
scripts.

Signed-off-by: Stacy Harper <contact@stacyharper.net>
Signed-off-by: Maarten van Gompel <proycon@anaproy.nl>

scripts/modem/sxmo_modemsendsms.sh

@@ -5,7 +5,7 @@
 . "$(dirname "$0")/sxmo_common.sh"
 
 info() {
-	echo "$1" > /dev/stderr
+	echo "$1" >> /dev/stderr
 }
 
 err() {