arm64/arch-lock: typedef mcs_lock_t

Was done in x86_64 for fileobj in commit 249bda4aef ("fileobj: use
MCS locks for per-file page hash")

Change-Id: I61957de336b6657687803e6288afed9360a42032

arch/arm64/kernel/include/arch-lock.h

@@ -152,6 +152,8 @@ typedef struct mcs_lock_node {
 	unsigned long irqsave;
 } __attribute__((aligned(64))) mcs_lock_node_t;
 
+typedef mcs_lock_node_t mcs_lock_t;
+
 static void mcs_lock_init(struct mcs_lock_node *node)
 {
 	node->locked = 0;