MIPS: SGI-IP27: micro-optimize arch_init_irq()

The function sets adjasted groups of bits in hub_irq_map by using
for-loops. There's a bitmap_set() function dedicated to do this.

Because [0, CPU_CALL_B_IRQ] and [NI_BRDCAST_ERR_A, MSC_PANIC_INTR]
ranges belong to the same machine word, bitmap_set() would boil down
to an inline wrapper in both cases, avoiding generating a loop, whth
the associate overhead.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

Author: YuryNorov

arch/mips/sgi-ip27/ip27-irq.c

@@ -286,11 +286,8 @@ void __init arch_init_irq(void)
 	 * Mark these as reserved right away so they won't be used accidentally
 	 * later.
 	 */
-	for (i = 0; i <= CPU_CALL_B_IRQ; i++)
-		set_bit(i, hub_irq_map);
-
-	for (i = NI_BRDCAST_ERR_A; i <= MSC_PANIC_INTR; i++)
-		set_bit(i, hub_irq_map);
+	bitmap_set(hub_irq_map, 0, CPU_CALL_B_IRQ + 1);
+	bitmap_set(hub_irq_map, NI_BRDCAST_ERR_A, MSC_PANIC_INTR - NI_BRDCAST_ERR_A + 1);
 
 	fn = irq_domain_alloc_named_fwnode("HUB");
 	WARN_ON(fn == NULL);