使用不同的优化等级会出现不同的效果
当使用-O0 等级时，无法正确得到关闭中断之前的状态

Using different optimization levels will have different effects
When the - o0 level is used, the state before the shutdown interrupt cannot be obtained correctly

previous rt_hw_context_switch might cause the
task switch handling error.

See
https://github.com/Nuclei-Software/nuclei-sdk/commit/1a1a209e9363840d372c04b84ce733ea6b6e79f2#diff-ba922e02206af6c52163f0c34a7e76e427b7ea22f791329b62f2069241c57778Signed-off-by: Huaqi Fang <578567190@qq.com>

This reverts commit e7fc0c89.

add qemu-riscv-virt64 bsp

1. 去除start_gcc.s中set_secondary_cpu_boot_address代码，这部分提取到qemu-vexpress-a9 bsp中。
2. 移动cpu.c中rt_hw_cpu_id函数到cp15_gcc.s，使用汇编实现，采用wake属性，方便bsp根据cpu特性获取CPU ID（多cpu集群中，不同厂家使用组合不一样）.
3. 整理start_gcc.s 适应多核启动，原来的代码只考虑到双核的情况。