crypto: fix nettle config check for running pbkdf test

The pbkdf test is being built based on a check for CONFIG_NETTLE.
As of fff2f982, it should be
instead checking CONFIG_NETTLE_KDF
Reported-by: N"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Tested-by: NBruce Rogers <brogers@suse.com>
Tested-by: NEd Maste <emaste@freebsd.org>
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

tests/Makefile

@@ -92,7 +92,7 @@ check-unit-$(CONFIG_GNUTLS) += tests/test-io-channel-tls$(EXESUF)
 check-unit-y += tests/test-io-channel-command$(EXESUF)
 check-unit-y += tests/test-io-channel-buffer$(EXESUF)
 check-unit-y += tests/test-base64$(EXESUF)
-check-unit-$(if $(CONFIG_NETTLE),y,$(CONFIG_GCRYPT_KDF)) += tests/test-crypto-pbkdf$(EXESUF)
+check-unit-$(if $(CONFIG_NETTLE_KDF),y,$(CONFIG_GCRYPT_KDF)) += tests/test-crypto-pbkdf$(EXESUF)
 check-unit-y += tests/test-crypto-ivgen$(EXESUF)
 check-unit-y += tests/test-crypto-afsplit$(EXESUF)
 check-unit-y += tests/test-crypto-xts$(EXESUF)