hw/loongarch: Move boot functions to boot.c

Move some boot functions to boot.c and struct
loongarch_boot_info into struct LoongArchMachineState.

Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20240426091551.2397867-2-gaosong@loongson.cn>
5 files changed