x86/Kconfig: Simplify X86_IO_APIC dependencies

Since dependencies are transitive, we don't really need to
repeat those of X86_UP_IOAPIC.

Furthermore avoid the symbol getting entered into .config when
it is off by having the default simply Y and the dependencies
solely handled via the intended for that purpose "depends on".

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/54D39BC9020000780005D688@mail.emea.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Kconfig

@@ -893,8 +893,8 @@ config X86_LOCAL_APIC
 	select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
 
 config X86_IO_APIC
-	def_bool X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC
-	depends on X86_LOCAL_APIC
+	def_bool y
+	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
 	select IRQ_DOMAIN
 
 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS