sparseirq: fix !SMP && !PCI_MSI && !HT_IRQ build

Ingo Molnar wrote:

>>>  drivers/pci/intr_remapping.c: In function 'irq_2_iommu_alloc':
>>>  drivers/pci/intr_remapping.c:72: error: 'boot_cpu_id' undeclared (first use in this function)
>>>  drivers/pci/intr_remapping.c:72: error: (Each undeclared identifier is reported only once
>>>  drivers/pci/intr_remapping.c:72: error: for each function it appears in.)

sparseirq should only be used with SMP for now.

arch/x86/Kconfig

@@ -240,7 +240,7 @@ config X86_HAS_BOOT_CPU_ID
 
 config SPARSE_IRQ
 	bool "Support sparse irq numbering"
-	depends on PCI_MSI || HT_IRQ
+	depends on (PCI_MSI || HT_IRQ) && SMP
 	default y
 	help
 	  This enables support for sparse irq, esp for msi/msi-x. You may need