[MLBEDSW-2787] Remove op.attrs["rescale"] in softmax.py

Added RescaleAdd operation to avoid non-standard attribute
"rescale" for Add operation. Also changed ResizeBilinear
in the same way.

Signed-off-by: Fredrik Svedberg <fredrik.svedberg@arm.com>
Change-Id: I1d286f63890585c06b8a161df1ff77e3f844a4b9
diff --git a/ethosu/vela/register_command_stream_generator.py b/ethosu/vela/register_command_stream_generator.py
index fa56d35..7de3d9a 100644
--- a/ethosu/vela/register_command_stream_generator.py
+++ b/ethosu/vela/register_command_stream_generator.py
@@ -637,7 +637,7 @@
         ofm_scale_f64 = np.double(ofm_quant.scale_f32)
         scale, shift = scaling.quantise_scale(ifm_scale_f64 / ofm_scale_f64)
     elif pool_op.rescale is not None:
-        # for ResizeBilinear operations with "rescale" in primary_op.attrs
+        # for ResizeBilinear operations with rescale
         rescale = pool_op.rescale
         rescale_bits = len(bin(round_up_to_int(rescale))) - 2 + 1
         scale, shift = scaling.quantise_pooling_scale(kernel.height * kernel.width, rescale_bits)