[mlir][tosa] Implement dynamic shape support for tosa.max_pool2d lowering (#87538)

The existing lowering for tosa.max_pool2d only supports dynamic
dimensions when the dynamic dimension is the batch dimension. This
change updates the lowering to support arbitrary dynamic dimensions on
the inputs and outputs of the tosa.max_pool2d operation.

This change also fixes a bug in the implementation of implicit
broadcasting in the tosa-to-linalg pass, which was introducing uses of
constant ops that violated dominance requirements.