crypto: des_s390 - Permit weak keys unless REQ_WEAK_KEY set

Just started running fips cavs test vectors through an s390x system
for giggles, and discovered that I missed patching s390's arch-specific
des3 implementation w/an earlier des3 patch to permit weak keys.

This change adds the same flag tweaks as
ad79cdd7 (crypto: des3_ede - permit
weak keys unless REQ_WEAK_KEY set) for s390's des3 implementation,
yields expected test results now.

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>