x86: Set serial port IRQ for SMSC LPC47M

For starting a Linux console on the superio serial port under
interrupt mode, the IRQ number must be configured.

Signed-off-by: Jian Luo <jian.luo4@boschrexroth.de>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/ibmpc.h b/arch/x86/include/asm/ibmpc.h
index c3b5187..678cde4 100644
--- a/arch/x86/include/asm/ibmpc.h
+++ b/arch/x86/include/asm/ibmpc.h
@@ -21,4 +21,7 @@
 #define UART0_BASE	0x3f8
 #define UART1_BASE	0x2f8
 
+#define UART0_IRQ	4
+#define UART1_IRQ	3
+
 #endif