f2fs: Add a segment type check in inplace write

This patch add a segment type check in IPU, in
case of something wrong with blkadd in dnode.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>