northbridge/intel/x4x: clean up includes

- Don't redefine D0F0_PCIEXBAR_LO, use the #define in x4x.h
- Move TPMBASE and TPM32() definitions into iomap.h
- Use "" style include for x4x.h in nortbridge files.
- Move includes of .h files out of x4x.h and into the c files that need
them.
- Protect function definitions in bootblock.

Change-Id: I3fdb579235c5446733a0ffba05fffe1a73381251
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/12849
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/northbridge/intel/x4x/bootblock.c

@@ -15,10 +15,8 @@
  */
 
 #include <arch/io.h>
-
-#define D0F0_PCIEXBAR_LO 0x60
-#define TPMBASE 0xfed40000
-#define TPM32(x) *((volatile u32 *)(TPMBASE + x))
+#include "iomap.h"
+#include "x4x.h"
 
 static void bootblock_northbridge_init(void)
 {