genirq: Provide default irq init flags

Arch code sets it's own irq_desc.status flags right after boot and for
dynamically allocated interrupts. That might involve iterating over a
huge array.

Allow ARCH_IRQ_INIT_FLAGS to set separate flags aside of IRQ_DISABLED
which is the default.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 78ff426..29963f9 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -39,7 +39,7 @@
 #ifdef CONFIG_SPARSE_IRQ
 
 static struct irq_desc irq_desc_init = {
-	.status		= IRQ_DISABLED,
+	.status		= IRQ_DEFAULT_INIT_FLAGS,
 	.handle_irq	= handle_bad_irq,
 	.depth		= 1,
 	.lock		= __RAW_SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
@@ -113,7 +113,7 @@
 
 static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
 	[0 ... NR_IRQS_LEGACY-1] = {
-		.status		= IRQ_DISABLED,
+		.status		= IRQ_DEFAULT_INIT_FLAGS,
 		.handle_irq	= handle_bad_irq,
 		.depth		= 1,
 		.lock		= __RAW_SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
@@ -204,7 +204,7 @@
 
 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 	[0 ... NR_IRQS-1] = {
-		.status		= IRQ_DISABLED,
+		.status		= IRQ_DEFAULT_INIT_FLAGS,
 		.handle_irq	= handle_bad_irq,
 		.depth		= 1,
 		.lock		= __RAW_SPIN_LOCK_UNLOCKED(irq_desc->lock),