f2fs: fix to allow node segment for GC by ioctl path

Allow node type segments also to be GC'd via f2fs ioctl
F2FS_IOC_GARBAGE_COLLECT_RANGE.

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