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>

arch/x86/Kconfig

@@ -250,7 +250,7 @@ config SPARSE_IRQ
 
 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.

arch/x86/kernel/io_apic.c

@@ -2471,7 +2471,7 @@ static void irq_complete_move(struct irq_desc **descp)
 		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);

kernel/irq/numa_migrate.c

 /*
- * linux/kernel/irq/handle.c
- *
- * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
- * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
- *
- * This file contains the core interrupt handling code.
- *
- * Detailed information is available in Documentation/DocBook/genericirq
+ * NUMA irq-desc migration code
  *
+ * Migrate IRQ data structures (irq_desc, chip_data, etc.) over to
+ * the new "home node" of the IRQ.
  */
 
 #include <linux/irq.h>