hw/riscv/riscv-iommu: Remove definition of RISCVIOMMU[Pci|Sys]Class

hw/riscv/riscv-iommu: Remove definition of RISCVIOMMU[Pci|Sys]Class

RISCVIOMMUPciClass and RISCVIOMMUSysClass are defined with missed
parent class, class_init on them may corrupt their parent class
fields.

It's lucky that parent_realize and parent_phases are not initialized
or used until now, so just remove the definitions. They can be added
back when really necessary.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250606092406.229833-6-zhenzhong.duan@intel.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>