Add negative testing support to RESCALE

 * Negative tests for rescale op added

Signed-off-by: Matthew Haddon <matthew.haddon@arm.com>
Change-Id: I70aead1c6a67f159c7b7c9a05f7d5f0b92521584
diff --git a/verif/tosa_error_if.py b/verif/tosa_error_if.py
index 2daeb9d..5e219cc 100644
--- a/verif/tosa_error_if.py
+++ b/verif/tosa_error_if.py
@@ -40,5 +40,7 @@
     PadSmallerZero = "PadSmallerZero"
     PadLargerEqualKernel = "PadLargerEqualKernel"
     PoolingOutputShapeMismatch = "PoolingOutputShapeMismatch"
+    ScaleNotTrue = "ScaleNotTrue"
+    ScaleTrue = "ScaleTrue"