sparseirq: fix numa_migrate_irq_desc dependency and comments

Impact: reduce kconfig variable scope and clean up

Bartlomiej pointed out that the config dependencies and comments are not right.

update it depend to NUMA, and fix some comments

Reported-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 60a0088..5c24382 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -250,7 +250,7 @@
 
 config NUMA_MIGRATE_IRQ_DESC
 	bool "Move irq desc when changing irq smp_affinity"
-	depends on SPARSE_IRQ && SMP
+	depends on SPARSE_IRQ && NUMA
 	default n
 	help
 	  This enables moving irq_desc to cpu/node that irq will use handled.
diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index bfe1245..a74887b 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -2471,7 +2471,7 @@
 		if (likely(!cfg->move_desc_pending))
 			return;
 
-		/* domain is not change, but affinity is changed */
+		/* domain has not changed, but affinity did */
 		me = smp_processor_id();
 		if (cpu_isset(me, desc->affinity)) {
 			*descp = desc = move_irq_desc(desc, me);