crypto: xts - Propagate NEED_FALLBACK bit

crypto: xts - Propagate NEED_FALLBACK bit

BugLink: http://bugs.launchpad.net/bugs/1672544
commit 89027579bc6c2febbcc9c2f9d5069adf71539e4b upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>