MLBEDSW-2804: Bias data type check wrong

 - Fixed bias check to use quantised values.

Signed-off-by: Tim Hall <tim.hall@arm.com>
Change-Id: I6d87439938b9b5aeec87814e5a30d59fd06d5748
diff --git a/ethosu/vela/supported_operators.py b/ethosu/vela/supported_operators.py
index 8ec7720..591f080 100644
--- a/ethosu/vela/supported_operators.py
+++ b/ethosu/vela/supported_operators.py
@@ -421,8 +421,8 @@
 
         # check if values fits in 40-bit
         if bias_tensor.dtype == DataType.int64:
-            for value in bias_tensor.values:
-                if not (-(1 << 39) <= value < (1 << 39)):
+            for quant_value in bias_tensor.quant_values:
+                if not (-(1 << 39) <= quant_value < (1 << 39)):
                     return False
 
         return True