TOSA: Added support for ADD, SUB and MUL

Added support for ADD, SUB and MUL

Signed-off-by: Patrik Gustavsson <patrik.gustavsson@arm.com>
Change-Id: I52acdc126b16e2cf4096bcf7a77023ea7d204998
diff --git a/ethosu/vela/weight_compressor.py b/ethosu/vela/weight_compressor.py
index 10a1a6d..6881703 100644
--- a/ethosu/vela/weight_compressor.py
+++ b/ethosu/vela/weight_compressor.py
@@ -314,7 +314,7 @@
     # No cache hit, need to perform the encoding
     if do_weights:
         assert weight_tens.quantization is not None
-        assert weight_tens.quantization.scale_f32 is not None
+        assert weight_tens.quantization.scale_f32 is not None or op.explicit_scaling
         assert weight_tens.quantization.zero_point is not None
 
         # Early zero-point correction