target/riscv: Remove target_ulong use in get_physical_address()

Use uint32_t for RV32, uint64_t otherwise.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>
Message-ID: <20260527201348.29511-6-philmd@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>