dm-default-key: fix wrong encryption/decryption when f2fs moves blocks

commit 2b425b7413e2 ("dm-default-key, f2fs, ICE: support dm-default-key with f2fs/ICE")

supports bio->bi_crypt_skip, so this patch should address the original issue by
adding this condition.

Change-Id: I215cd9d02e364af07eebf388000809cdf0cce472
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Signed-off-by: Shivaprasad Hongal <shongal@codeaurora.org>
Signed-off-by: Neeraj Soni <neersoni@codeaurora.org>