There is no good reason to allow this mount option when the kernel isn't
configured with encryption support.  Since this option is only for
testing, we can just fix this; we don't really need to worry about
breaking anyone who might be counting on this option being ignored.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>