f2fs: fix to use correct segment type in f2fs_allocate_data_block()

@type in f2fs_allocate_data_block() indicates log header's type, it
can be CURSEG_COLD_DATA_PINNED or CURSEG_ALL_DATA_ATGC, rather than
type of data/node, however IS_DATASEG()/IS_NODESEG() only accept later
one, fix it.

Fixes: 093749e2 ("f2fs: support age threshold based garbage collection")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>