s390/uaccess: simplify control register updates

Always switch to the kernel ASCE in switch_mm. Load the secondary
space ASCE in finish_arch_post_lock_switch after checking that
any pending page table operations have completed. The primary
ASCE is loaded in entry[64].S. With this the update_primary_asce
call can be removed from the switch_to macro and from the start
of switch_mm function. Remove the load_primary argument from
update_user_asce/clear_user_asce, rename update_user_asce to
set_user_asce and rename update_primary_asce to load_kernel_asce.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/mm/pgtable.c

@@ -53,8 +53,10 @@ static void __crst_table_upgrade(void *arg)
 {
 	struct mm_struct *mm = arg;
 
-	if (current->active_mm == mm)
-		update_user_asce(mm, 1);
+	if (current->active_mm == mm) {
+		clear_user_asce();
+		set_user_asce(mm);
+	}
 	__tlb_flush_local();
 }
 
@@ -108,7 +110,7 @@ void crst_table_downgrade(struct mm_struct *mm, unsigned long limit)
 	pgd_t *pgd;
 
 	if (current->active_mm == mm) {
-		clear_user_asce(mm, 1);
+		clear_user_asce();
 		__tlb_flush_mm(mm);
 	}
 	while (mm->context.asce_limit > limit) {
@@ -134,7 +136,7 @@ void crst_table_downgrade(struct mm_struct *mm, unsigned long limit)
 		crst_table_free(mm, (unsigned long *) pgd);
 	}
 	if (current->active_mm == mm)
-		update_user_asce(mm, 1);
+		set_user_asce(mm);
 }
 #endif