x86: Compile irq.c for 64-bit

There is no reason not to compile irq.c for 64-bit.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/Makefile b/arch/x86/cpu/Makefile
index 45f95ab..92a9023 100644
--- a/arch/x86/cpu/Makefile
+++ b/arch/x86/cpu/Makefile
@@ -35,8 +35,8 @@
 obj-$(CONFIG_INTEL_QUARK) += quark/
 obj-$(CONFIG_INTEL_QUEENSBAY) += queensbay/
 obj-y += lapic.o ioapic.o
-ifndef CONFIG_$(SPL_)X86_64
 obj-y += irq.o
+ifndef CONFIG_$(SPL_)X86_64
 obj-$(CONFIG_SMP) += mp_init.o
 endif
 obj-y += mtrr.o