xfs_io/encrypt: update to UAPI definitions from Linux v5.4

xfs_io/encrypt: update to UAPI definitions from Linux v5.4

Update to the latest fscrypt UAPI definitions, including:

- New names for some existing definitions (FSCRYPT_ instead of FS_).
- New ioctls.
- New encryption mode numbers and flags.

This patch doesn't make any change to the program logic itself.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>