f2fs: fix using wrong 'submitted' value in f2fs_write_cache_pages

When f2fs_write_single_data_page fails, f2fs_write_cache_pages
will use the last 'submitted' value incorrectly, which will cause
'nwritten' and 'wbc->nr_to_write' calculation errors

Signed-off-by: zangyangyang1 <zangyangyang1@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>