interrupts: new static IRQ API

The interrupt API has been redesigned:

- irq_connect() for dynamic interrupts renamed to irq_connect_dynamic().
  It will be used in situations where the new static irq_connect()
  won't work, i.e. the value of arguments can't be computed at build time
- a new API for static interrupts replaces irq_connect(). it is used
  exactly the same way as its dynamic counterpart. The old static irq
  macros will be removed
- Separate stub assembly files are no longer needed as the stubs are now
  generated inline with irq_connect()

ReST documentation updated for the changed API. Some detail about the
IDT in ROM added, and an oblique reference to the internal-only
_irq_handler_set() API removed; we don't talk about internal APIs in
the official documentation.

Change-Id: I280519993da0e0fe671eb537a876f67de33d3cd4
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

drivers/timer/arcv2_timer0.c

@@ -311,9 +311,6 @@ static void tickless_idle_init(void) {}
  */
 int _sys_clock_driver_init(struct device *device)
 {
-	int irq = CONFIG_ARCV2_TIMER0_INT_LVL;
-	int prio = CONFIG_ARCV2_TIMER0_INT_PRI;
-
 	ARG_UNUSED(device);
 
 	/* ensure that the timer will not generate interrupts */
@@ -322,7 +319,8 @@ int _sys_clock_driver_init(struct device *device)
 
 	cycles_per_tick = sys_clock_hw_cycles_per_tick;
 
-	(void)irq_connect(irq, prio, _timer_int_handler, 0, 0);
+	irq_connect(CONFIG_ARCV2_TIMER0_INT_LVL, CONFIG_ARCV2_TIMER0_INT_PRI,
+		    _timer_int_handler, 0, 0);
 
 	/*
 	 * Set the reload value to achieve the configured tick rate, enable the