powerpc: Convert hugepd_free() to use call_rcu()

Now that call_rcu()'s callback is not invoked until after all
preempt-disable regions of code have completed (in addition to explicitly
marked RCU read-side critical sections), call_rcu() can be used in place
of call_rcu_sched().  This commit therefore makes that change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: <linuxppc-dev@lists.ozlabs.org>

arch/powerpc/mm/hugetlbpage.c

@@ -289,7 +289,7 @@ static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
 
 	(*batchp)->ptes[(*batchp)->index++] = hugepte;
 	if ((*batchp)->index == HUGEPD_FREELIST_SIZE) {
-		call_rcu_sched(&(*batchp)->rcu, hugepd_free_rcu_callback);
+		call_rcu(&(*batchp)->rcu, hugepd_free_rcu_callback);
 		*batchp = NULL;
 	}
 	put_cpu_var(hugepd_freelist_cur);