feat: [libcpu/c906] support ARCH_REMAP_KERNEL
This change was necessary to enable the remapping of the kernel image to
a high virtual address region on the c906 platform.
Changes:
- Introduced new configuration options `ARCH_REMAP_KERNEL`, and
`ARCH_USING_ASID` under the `ARCH_RISCV64` section.
- Updated MMU initialization and switching functions to incorporate
remapping handling.
- Modified page table setup for proper memory attribute settings.
- Added support for early memory setup, kernel remapping
- Added conditional compilation for ASID support in the `rt_aspace` struct,
since this is not enable currently for most architecture.
Signed-off-by: Shell <smokewood@qq.com>