f2fs: compress tmp files given extension

Let's compress tmp files for the given extension list.

This patch does not change the previous behavior, but allow the cases as below.

Extention example: "ext"

- abc.ext : allow
- abc.ext.abc : allow
- abc.extm : not allow

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