change options for numerical comparision

use directory test option for cpufreq test and add warning message
for hotplug 07 test

Signed-off-by: Carlos Hernandez <ceh@ti.com>
Signed-off-by: Sanjay Singh Rawat <sanjay.rawat@linaro.org>
diff --git a/thermal/thermal_04.sh b/thermal/thermal_04.sh
index 9275dcf..99a3430 100755
--- a/thermal/thermal_04.sh
+++ b/thermal/thermal_04.sh
@@ -31,7 +31,7 @@
 pid=0
 
 heater_kill() {
-    if [ $pid != 0 ]; then
+    if [ $pid -ne 0 ]; then
 	kill -9 $pid
     fi
 }