ahci: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly. Adds a pointer back to link
structure.

Signed-off-by: Kees Cook <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Acked-by: Tejun Heo <[e-mail]>
Cc: [e-mail]
Link: https://lkml.kernel.org/r/20171016215658.GA101965@beast

drivers/ata/ahci.h

···
 	unsigned long saved_activity;
 	unsigned long activity;
 	unsigned long led_state;
+	struct ata_link *link;
 };
 
 struct ahci_port_priv {

drivers/ata/libahci.c

···
 		mod_timer(&emp->timer, jiffies + msecs_to_jiffies(10));
 }
 
-static void ahci_sw_activity_blink(unsigned long arg)
+static void ahci_sw_activity_blink(struct timer_list *t)
 {
-	struct ata_link *link = (struct ata_link *)arg;
+	struct ahci_em_priv *emp = from_timer(emp, t, timer);
+	struct ata_link *link = emp->link;
 	struct ata_port *ap = link->ap;
-	struct ahci_port_priv *pp = ap->private_data;
-	struct ahci_em_priv *emp = &pp->em_priv[link->pmp];
+
 	unsigned long led_message = emp->led_state;
 	u32 activity_led_state;
 	unsigned long flags;
···
 
 	/* init activity stats, setup timer */
 	emp->saved_activity = emp->activity = 0;
-	setup_timer(&emp->timer, ahci_sw_activity_blink, (unsigned long)link);
+	emp->link = link;
+	timer_setup(&emp->timer, ahci_sw_activity_blink, 0);
 
 	/* check our blink policy and set flag for link if it's enabled */
 	if (emp->blink_policy)