x86: Enable forced interrupt threading support

All non threadeable interrupts are marked. Enable forced irq threading
support.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig

@@ -67,6 +67,7 @@ config X86
 	select GENERIC_IRQ_PROBE
 	select GENERIC_PENDING_IRQ if SMP
 	select GENERIC_IRQ_SHOW
+	select IRQ_FORCED_THREADING
 	select USE_GENERIC_SMP_HELPERS if SMP
 
 config INSTRUCTION_DECODER