Add tflite-opaque-delegate flag in build-tool validation script

Signed-off-by: Nikhil Raj <nikhil.raj@arm.com>
Change-Id: I402a4c74610b5dc8a3ca6e22218b58fbe59474ed
diff --git a/build-tool/scripts/validation.sh b/build-tool/scripts/validation.sh
index 12988b6..48b2372 100755
--- a/build-tool/scripts/validation.sh
+++ b/build-tool/scripts/validation.sh
@@ -33,7 +33,7 @@
 fi
 
 # Validation of chosen Arm NN dependencies
-if [ "$flag_tflite_delegate" -eq 0 ] && [ "$flag_tflite_parser" -eq 0 ] && [ "$flag_onnx_parser" -eq 0 ]; then
+if [ "$flag_tflite_classic_delegate" -eq 0 ] && [ "$flag_tflite_opaque_delegate" -eq 0 ] && [ "$flag_tflite_parser" -eq 0 ] && [ "$flag_onnx_parser" -eq 0 ]; then
   echo "$name: at least one of flags --tflite-classic-delegate, --tflite-opaque-delegate, --tflite-parser or --onnx-parser must be set (or --all)."
   exit 1
 fi