usb: musb: avoid NULL pointer dereference

instead of relying on the otg pointer, which
can be NULL in certain cases, we can use the
gadget and host pointers we already hold inside
struct musb.

Cc: <stable@vger.kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.c

@@ -438,7 +438,6 @@ void musb_hnp_stop(struct musb *musb)
 static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb,
 				u8 devctl)
 {
-	struct usb_otg *otg = musb->xceiv->otg;
 	irqreturn_t handled = IRQ_NONE;
 
 	dev_dbg(musb->controller, "<== DevCtl=%02x, int_usb=0x%x\n", devctl,
@@ -653,7 +652,7 @@ static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb,
 				break;
 		case OTG_STATE_B_PERIPHERAL:
 			musb_g_suspend(musb);
-			musb->is_active = otg->gadget->b_hnp_enable;
+			musb->is_active = musb->g.b_hnp_enable;
 			if (musb->is_active) {
 				musb->xceiv->state = OTG_STATE_B_WAIT_ACON;
 				dev_dbg(musb->controller, "HNP: Setting timer for b_ase0_brst\n");
@@ -669,7 +668,7 @@ static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb,
 			break;
 		case OTG_STATE_A_HOST:
 			musb->xceiv->state = OTG_STATE_A_SUSPEND;
-			musb->is_active = otg->host->b_hnp_enable;
+			musb->is_active = musb->hcd->self.b_hnp_enable;
 			break;
 		case OTG_STATE_B_HOST:
 			/* Transition to B_PERIPHERAL, see 6.8.2.6 p 44 */