x86: Add some missing includes

I suspect these includes were usually available because something else
included them earlier or because they were brought in transitively.

Change-Id: I6aae2ac94dc792eac6febb4345e8125f69f70988
Signed-off-by: Gabe Black <gabeblack@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/include/asm/u-boot.h

@@ -36,6 +36,9 @@
 #ifndef _U_BOOT_H_
 #define _U_BOOT_H_	1
 
+#include <config.h>
+#include <compiler.h>
+
 typedef struct bd_info {
 	unsigned long	bi_memstart;	/* start of DRAM memory */
 	phys_size_t	bi_memsize;	/* size	 of DRAM memory in bytes */