f2fs: check cap_resource only for data blocks

Cherry-pick from origin/upstream-f2fs-stable-linux-3.18.y:
commit dae6d196 ("f2fs: check cap_resource only for data blocks")

This patch changes the rule to check cap_resource for data blocks, not inode
or node blocks in order to avoid selinux denial.

Change-Id: I02bc7b9eb78b64323d71cb945850b2c4828dcebd
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>