hw/mips/loongson3_virt: Emulate suspend function

hw/mips/loongson3_virt: Emulate suspend function

Suspend function is emulated as what hardware actually do.
Doorbell register fields are updates to include suspend value,
suspend vector is encoded in firmware blob and fw_cfg is updated
to include S3 bits as what x86 did.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-ID: <20240508-loongson3v-suspend-v1-1-186725524a39@flygoat.com>
[PMD: Use g_memdup2(), constify suspend array]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>