initrd.scripts: text if ${device} is set before messing with /sys/power

defaults/initrd.scripts

@@ -1272,7 +1272,8 @@ do_resume() {
 swsusp_resume() {
 	# determine swap resume partition
 	local device=$(ls -lL "${REAL_RESUME}" | sed 's/\  */ /g' | cut -d \  -f 5-6 | sed 's/,\ */:/')
-	[ -f /sys/power/resume ] && echo "${device}" > /sys/power/resume
+	[ -f /sys/power/resume -a -n "${device}" ] && \
+		echo "${device}" > /sys/power/resume
 }
 
 tuxonice_resume() {