[FAB-4429] LTE tool driver: put proper exit code

This change makes sure that the driver exits with code 1 in the event of
invalid or empty test names.

Change-Id: I284fcabe1ef94bb9033e678d4abb89bac49cf679
Signed-off-by: Adnan Choudhury <adnan.choudhury@itpeoplecorp.com>

test/tools/LTE/scripts/runbenchmarks.sh

@@ -122,4 +122,5 @@ runLargeDataExperiment\n"
     runLargeDataExperiment ;;
   *)
     printf "Error: test name empty/incorrect!\n"  >> /dev/stderr
+    exit 1 ;;
 esac