f2fs: fix retry logic in f2fs_write_cache_pages()

In case a compressed file is getting overwritten, the current retry
logic doesn't include the current page to be retried now as it sets
the new start index as 0 and new end index as writeback_index - 1.
This causes the corresponding cluster to be uncompressed and written
as normal pages without compression. Fix this by allowing writeback to
be retried for the current page as well (in case of compressed page
getting retried due to index mismatch with cluster index). So that
this cluster can be written compressed in case of overwrite.

Also, align f2fs_write_cache_pages() according to the change -
<64081362>("mm/page-writeback.c: fix range_cyclic writeback vs
writepages deadlock").

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>