s390/crypto: Fix return code checking in cbc_paes_crypt()

The return code of cpacf_kmc() is less than the number of
bytes to process in case of an error, not greater.
The crypt routines for the other cipher modes already have
this correctly.

Cc: stable@vger.kernel.org # v4.11+
Fixes: 27937843 ("s390/crypt: Add protected key AES module")
Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>
Acked-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/crypto/paes_s390.c

@@ -208,7 +208,7 @@ static int cbc_paes_crypt(struct blkcipher_desc *desc, unsigned long modifier,
 			      walk->dst.virt.addr, walk->src.virt.addr, n);
 		if (k)
 			ret = blkcipher_walk_done(desc, walk, nbytes - k);
-		if (n < k) {
+		if (k < n) {
 			if (__cbc_paes_set_key(ctx) != 0)
 				return blkcipher_walk_done(desc, walk, -EIO);
 			memcpy(param.key, ctx->pk.protkey, MAXPROTKEYSIZE);