crypto: xts - Propagate NEED_FALLBACK bit
When we're used as a fallback algorithm, we should propagate
the NEED_FALLBACK bit when searching for the underlying ECB mode.
This just happens to fix a hang too because otherwise the search
may end up loading the same module that triggered this XTS creation.
Cc: stable@vger.kernel.org #4.10
Fixes: f1c131b45410 ("crypto: xts - Convert to skcipher")
Reported-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>