[IA64] fix NULL pointer in ia64/irq_chip-mask/unmask function

This patch fixes boot failure because irq_desc->mask() is NULL.

- Added mask/unmask functions to ia64's irq desc function table.
- rename hw_interrupt_type to irq_chip. hw_interrupt_type is old name.
- Tony: Added same change to arch/ia64/sn/kernel/irq.c as pointed out
  by Eric Biederman ... mask/unmask functions there can be no-op.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/iosapic.c

@@ -446,7 +446,7 @@ iosapic_end_level_irq (unsigned int irq)
 #define iosapic_disable_level_irq	mask_irq
 #define iosapic_ack_level_irq		nop
 
-struct hw_interrupt_type irq_type_iosapic_level = {
+struct irq_chip irq_type_iosapic_level = {
 	.name =		"IO-SAPIC-level",
 	.startup =	iosapic_startup_level_irq,
 	.shutdown =	iosapic_shutdown_level_irq,
@@ -454,6 +454,8 @@ struct hw_interrupt_type irq_type_iosapic_level = {
 	.disable =	iosapic_disable_level_irq,
 	.ack =		iosapic_ack_level_irq,
 	.end =		iosapic_end_level_irq,
+	.mask =		mask_irq,
+	.unmask =	unmask_irq,
 	.set_affinity =	iosapic_set_affinity
 };
 
@@ -493,7 +495,7 @@ iosapic_ack_edge_irq (unsigned int irq)
 #define iosapic_disable_edge_irq	nop
 #define iosapic_end_edge_irq		nop
 
-struct hw_interrupt_type irq_type_iosapic_edge = {
+struct irq_chip irq_type_iosapic_edge = {
 	.name =		"IO-SAPIC-edge",
 	.startup =	iosapic_startup_edge_irq,
 	.shutdown =	iosapic_disable_edge_irq,
@@ -501,6 +503,8 @@ struct hw_interrupt_type irq_type_iosapic_edge = {
 	.disable =	iosapic_disable_edge_irq,
 	.ack =		iosapic_ack_edge_irq,
 	.end =		iosapic_end_edge_irq,
+	.mask =		mask_irq,
+	.unmask =	unmask_irq,
 	.set_affinity =	iosapic_set_affinity
 };