Unbinding `ff_currentcluster` and `f_pos`:
1. Added `ff_pos` in `struct fat_file_s`.
2. Added function `fat_zero_cluster` for doing zeroing for gap
between EOF and new position beyond EOF.
3. Added function `fat_get_sectors` for getting the sector where
`f_pos` is located, allocting new cluster when `f_pos` is beyond
EOF.
4. Modify function `fat_read`, and `fat_write` with above functions.
5. Remove redundant logics in `fat_seek` since now new cluster is
allocated when writing instead of seeking.
Signed-off-by: Yinzhe Wu <Yinzhe.Wu@sony.com>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Jacky Cao <Jacky.Cao@sony.com>
Tested-by: Yinzhe Wu <Yinzhe.Wu@sony.com>
479c393291