drivers/hwspinlock: use correct radix tree API

radix_tree_is_indirect_ptr() is an internal API. The correct call to
use is radix_tree_deref_retry() which has the appropriate unlikely()
annotation.

Fixes: c6400ba7e13a ("drivers/hwspinlock: fix race between radix tree insertion and lookup")
Signed-off-by: Matthew Wilcox <[e-mail]>
Cc: Konstantin Khlebnikov <[e-mail]>
Cc: Kirill Shutemov <[e-mail]>
Cc: Jan Kara <[e-mail]>
Cc: Neil Brown <[e-mail]>
Cc: Ross Zwisler <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/hwspinlock/hwspinlock_core.c

···
 		hwlock = radix_tree_deref_slot(slot);
 		if (unlikely(!hwlock))
 			continue;
-		if (radix_tree_is_indirect_ptr(hwlock)) {
+		if (radix_tree_deref_retry(hwlock)) {
 			slot = radix_tree_iter_retry(&iter);
 			continue;
 		}