flush all data cache for s5pv210.

N/A

1. Read Cache Level ID Register.
2. Write the cache size selection register.
3. Prefetch flush. The prefetch buffer is flushed.
4. Read current cache size identification register.
5. Invalidate Data or Unified cache line by Set/Way.
6. Finished.

Signed-off-by: liminghao <liminghao@xiaomi.com>