[Feature] 优化cromfs的内存消耗

[heyuanjie87]

Describe problem solved by the proposed feature

typedef struct { uint8_t *buff; } file_info; 这个缓冲区一次分配了整个文件大小的空间，当文件太大时就没法分到可用内存

Describe your preferred solution

No response

Describe possible alternatives

No response