sunrpc: Fix RFC6803 encryption test

The usage_data[] array in rfc6803_encrypt_case() is uninitialised, so clear
it as it may cause the tests to fail otherwise.

Fixes: b958cff ("SUNRPC: Add encryption KUnit tests for the RFC 6803 encryption types")
Link: https://lore.kernel.org/r/380323.1681314997@warthog.procyon.org.uk/
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Scott Mayhew <smayhew@redhat.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: linux-nfs@vger.kernel.org
cc: linux-crypto@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: dhowells

net/sunrpc/auth_gss/gss_krb5_test.c

@@ -1327,6 +1327,7 @@ static void rfc6803_encrypt_case(struct kunit *test)
 	if (!gk5e)
 		kunit_skip(test, "Encryption type is not available");
 
+	memset(usage_data, 0, sizeof(usage_data));
 	usage.data[3] = param->constant;
 
 	Ke.len = gk5e->Ke_length;