f2fs: fix a wrong condition in f2fs_skip_inode_update

Fix commit 97dd26ad8347 (f2fs: fix wrong AUTO_RECOVER condition).
We should use ~PAGE_MASK to determine whether i_size is aligned to
the f2fs's block size or not.

Signed-off-by: Junling Zheng <zhengjunling@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>