To support more choice on bootfs. romfs, cromfs are now supported on
risc_v_big platform.
Changes:
- added mount operations under port
- added prototypes for cromfs init APIs
Signed-off-by: Shell <smokewood@qq.com>
Reviewed-on: https://github.com/RT-Thread/rt-thread/pull/9229
Reviewed-by: Chen Wang <unicorn_wang@outlook.com>