x86/irq: Refine the way to calculate NR_IRQS

Now we have made MSI independent of IOAPIC, so we need to refine the
way to calculate NR_IRQS to support configuration with MSI enabled but
IOAPIC disabled.

Signed-off-by: Jiang Liu <[e-mail]>
Tested-by: Joerg Roedel <[e-mail]>
Cc: Konrad Rzeszutek Wilk <[e-mail]>
Cc: David Cohen <[e-mail]>
Cc: Sander Eikelenboom <[e-mail]>
Cc: David Vrabel <[e-mail]>
Cc: Tony Luck <[e-mail]>
Cc: Joerg Roedel <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Bjorn Helgaas <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Rafael J. Wysocki <[e-mail]>
Cc: Randy Dunlap <[e-mail]>
Cc: Yinghai Lu <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Dimitri Sivanich <[e-mail]>
Cc: Jan Beulich <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Thomas Gleixner <[e-mail]>

arch/x86/include/asm/irq_vectors.h

···
  * static arrays.
  */
 
-#define NR_IRQS_LEGACY			  16
+#define NR_IRQS_LEGACY			16
 
-#define IO_APIC_VECTOR_LIMIT		( 32 * MAX_IO_APICS )
+#define CPU_VECTOR_LIMIT		(64 * NR_CPUS)
+#define IO_APIC_VECTOR_LIMIT		(32 * MAX_IO_APICS)
 
-#ifdef CONFIG_X86_IO_APIC
-# define CPU_VECTOR_LIMIT		(64 * NR_CPUS)
-# define NR_IRQS					\
+#if defined(CONFIG_X86_IO_APIC) && defined(CONFIG_PCI_MSI)
+#define NR_IRQS						\
 	(CPU_VECTOR_LIMIT > IO_APIC_VECTOR_LIMIT ?	\
 		(NR_VECTORS + CPU_VECTOR_LIMIT)  :	\
 		(NR_VECTORS + IO_APIC_VECTOR_LIMIT))
-#else /* !CONFIG_X86_IO_APIC: */
-# define NR_IRQS			NR_IRQS_LEGACY
+#elif defined(CONFIG_X86_IO_APIC)
+#define	NR_IRQS				(NR_VECTORS + IO_APIC_VECTOR_LIMIT)
+#elif defined(CONFIG_PCI_MSI)
+#define NR_IRQS				(NR_VECTORS + CPU_VECTOR_LIMIT)
+#else
+#define NR_IRQS				NR_IRQS_LEGACY
 #endif
 
 #endif /* _ASM_X86_IRQ_VECTORS_H */