x86: Enable generic board support

This enables generic board support so that x86 boards can define
CONFIG_SYS_GENERIC_BOARD.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/board_r.c b/common/board_r.c
index 63c6936..9605f80 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -507,11 +507,13 @@
 #endif
 
 /* enable exceptions */
+#ifdef CONFIG_ARM
 static int initr_enable_interrupts(void)
 {
 	enable_interrupts();
 	return 0;
 }
+#endif
 
 #ifdef CONFIG_CMD_NET
 static int initr_ethaddr(void)