x86: Allow interrupt to happen once

At present the interrupt table is included in all phases of U-Boot. Allow
it to be omitted, e.g. in TPL, to reduce size.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/Makefile b/arch/x86/cpu/Makefile
index 6296b55..b6a010e 100644
--- a/arch/x86/cpu/Makefile
+++ b/arch/x86/cpu/Makefile
@@ -53,7 +53,7 @@
 obj-$(CONFIG_INTEL_QUEENSBAY) += queensbay/
 obj-$(CONFIG_INTEL_TANGIER) += tangier/
 obj-$(CONFIG_APIC) += lapic.o ioapic.o
-obj-y += irq.o
+obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += irq.o
 ifndef CONFIG_$(SPL_)X86_64
 obj-$(CONFIG_SMP) += mp_init.o
 endif