usb: musb: restore INDEX register in resume path

Restoring the missing INDEX register value in musb_restore_context().
Without this suspend resume functionality is broken with offmode
enabled.

Cc: stable@kernel.org
Acked-by: NAnand Gadiyar <gadiyar@ti.com>
Signed-off-by: NAjay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.c

@@ -2282,6 +2282,7 @@ static void musb_restore_context(struct musb *musb)
 				musb->context.index_regs[i].rxhubport);
 		}
 	}
+	musb_writeb(musb_base, MUSB_INDEX, musb->context.index);
 }
 
 static int musb_suspend(struct device *dev)