[MLBEDSW-2928] Add batching to softmax

Added batching to softmax by reshaping the input.

Signed-off-by: Fredrik Svedberg <fredrik.svedberg@arm.com>
Change-Id: I0b516f9bf2410fb86372b229beba4a7280c498cc
diff --git a/ethosu/vela/tensor.py b/ethosu/vela/tensor.py
index 83dc61a..49521e7 100644
--- a/ethosu/vela/tensor.py
+++ b/ethosu/vela/tensor.py
@@ -751,7 +751,7 @@
         elif d == 2:
             return [self.shape[0], 1, 1, self.shape[1]]
         else:
-            return self.shape
+            return self.shape.copy()
 
     def __str__(self):
         return "<nng.Tensor '%s' shape=%s dtype=%s>" % (self.name, self.shape, self.dtype)