ADT: Fix check_result script cond comparison bug

When meeting errors, the return number can't be directly compared with
-1. Actually, it might be represented as 255. The correct way is to
compared it with 0. If the result is non-zero number, we meet error.
This patch is for fixing [BUGID #742]

Signed-off-by: Liping Ke <liping.ke@intel.coom>

meta/recipes-devtools/installer/adt-installer/scripts/util

@@ -84,14 +84,14 @@ done
 
 check_result()
 {
-  result="$?"
-  if [  "$result" == "-1" ]; then
+  result=$?
+  if [ $result -eq 1 ]; then
+    exit -1
+  elif [  $result -ne 0 ]; then
      echo_info "\n#############################################################################"
      echo_info "# Meet error(s) when installing Yocto ADT! Please check log file for details. "
      echo_info "#############################################################################\n"
     exit -1
-  elif [ "$result" == "1" ]; then
-    exit -1
   fi
 }