MLBEDSW-10631: Rewrite CONST op

TOSA CONST operators does not have any input tensors, only an attribute containing a constant tensor and an output tensor. Until now, we've simply ignored the CONST operators in the TOSA reader since we're only interested in the constant output tensor. This causes issues in the case of a single CONST operator network, where ignoring CONST results in an optimized network without any operators, which our raw mode writer can not handle.

This patch replaces CONST operators with IDENTITY operators which gets cleaned up during RemoveReshape to either be removed completely or get converted to a memory copy when it is the last operator remaining in the network.

Signed-off-by: Rickard Bolin rickard.bolin@arm.com Change-Id: Icf18f0bad27a1220073574ffa2626f8838b4df69