padata: make padata_do_parallel to return zero on success

To return -EINPROGRESS on success in padata_do_parallel was
considered to be odd. This patch changes this to return zero
on success. Also the only user of padata, pcrypt is adapted to
convert a return of zero to -EINPROGRESS within the crypto layer.
This also removes the pcrypt fallback if padata_do_parallel
was called on a not running padata instance as we can't handle it
anymore. This fallback was unused, so it's save to remove it.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/kernel/padata.c b/kernel/padata.c
index 57ec4eb..ae8defc 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -111,10 +111,13 @@
 
 	pd = rcu_dereference(pinst->pd);
 
-	err = 0;
+	err = -EINVAL;
 	if (!(pinst->flags & PADATA_INIT))
 		goto out;
 
+	if (!cpumask_test_cpu(cb_cpu, pd->cpumask))
+		goto out;
+
 	err =  -EBUSY;
 	if ((pinst->flags & PADATA_RESET))
 		goto out;
@@ -122,11 +125,7 @@
 	if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
 		goto out;
 
-	err = -EINVAL;
-	if (!cpumask_test_cpu(cb_cpu, pd->cpumask))
-		goto out;
-
-	err = -EINPROGRESS;
+	err = 0;
 	atomic_inc(&pd->refcnt);
 	padata->pd = pd;
 	padata->cb_cpu = cb_cpu;