x86: Rename CONFIG_SYS_NUM_IRQS to SYS_NUM_IRQS

CONFIG_SYS_NUM_IRQS is actually not something we can configure,
but an architecture defined number of ISA IRQs. Move it from
x86-common.h to asm/interrupt.h and rename it to SYS_NUM_IRQS.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/interrupt.h b/arch/x86/include/asm/interrupt.h
index fcd766b..95a4de0 100644
--- a/arch/x86/include/asm/interrupt.h
+++ b/arch/x86/include/asm/interrupt.h
@@ -13,6 +13,8 @@
 
 #include <asm/types.h>
 
+#define SYS_NUM_IRQS	16
+
 /* Architecture defined exceptions */
 enum x86_exception {
 	EXC_DE = 0,