Save Int16/UINT16 test outputs to native dtypes

* Int16/UInt16 reference outputs were previously saved to INT32
* Save those in their native dtypes and updated other affected code

Signed-off-by: Jerry Ge <jerry.ge@arm.com>
Change-Id: I0c3b7fba096a8cb1ddabef20ad13498b8f46d36f
diff --git a/verif/generator/tosa_test_gen.py b/verif/generator/tosa_test_gen.py
index bc931dc..8440853 100644
--- a/verif/generator/tosa_test_gen.py
+++ b/verif/generator/tosa_test_gen.py
@@ -195,6 +195,10 @@
             return np.int8(self.rng.integers(low=low, high=high, size=shape))
         elif dtype == DType.UINT8:
             return np.uint8(self.rng.integers(low=low, high=high, size=shape))
+        elif dtype == DType.INT16:
+            return np.int16(self.rng.integers(low=low, high=high, size=shape))
+        elif dtype == DType.UINT16:
+            return np.uint16(self.rng.integers(low=low, high=high, size=shape))
         elif dtype in (DType.INT48, DType.SHAPE):
             return np.int64(self.rng.integers(low=low, high=high, size=shape))
         elif dtype in (