some minor cleanup of issues detected by shellcheck after applying the patch: 'modemmonitor: use dbus-monitor'

scripts/modem/sxmo_modemmonitor.sh

@@ -1,5 +1,4 @@
 #!/usr/bin/env sh
-TIMEOUT=3
 LOGDIR="$XDG_CONFIG_HOME"/sxmo/modem
 NOTIFDIR="$XDG_CONFIG_HOME"/sxmo/notifications
 trap "gracefulexit" INT TERM
@@ -127,12 +126,12 @@ checkfornewtexts() {
 mainloop() {
 	checkformissedcalls
 	dbus-monitor --system "interface='org.freedesktop.ModemManager1.Modem.Voice',type='signal',member='CallAdded'" | \
-		while read line; do
+		while read -r; do
 			checkforincomingcalls
 			checkformissedcalls
 		done &
 	dbus-monitor --system "interface='org.freedesktop.ModemManager1.Modem.Messaging',type='signal',member='Added'" | \
-		while read line; do
+		while read -r; do
 			checkfornewtexts
 		done &
 	wait