Add rank 0 testing support

Default test range is now rank 0 to 3 instead of 1 to 4

Signed-off-by: Jeremy Johnson <jeremy.johnson@arm.com>
Change-Id: Ibde66b60b58de9f4a3852a3807c01f8dae61206f
diff --git a/verif/generator/datagenerator.py b/verif/generator/datagenerator.py
index c63a2d5..9f3d29d 100644
--- a/verif/generator/datagenerator.py
+++ b/verif/generator/datagenerator.py
@@ -68,7 +68,11 @@
 
     def _create_buffer(self, dtype: str, shape: tuple):
         """Helper to create a buffer of the required type."""
-        size = np.prod(shape)
+        if shape:
+            size = np.prod(shape)
+        else:
+            # Rank 0
+            size = 1
 
         if dtype == "FP32":
             # Create buffer and initialize to zero