baytrail: Add header include wrapper and offset define

Since this file will get added to payloads it is useful if it
exports what offset in NVS it lives.

BUG=chrome-os-partner:24380
BRANCH=none
TEST=build and boot rambi with emmc in ACPI mode

Change-Id: I52860980c91dfe2525628e142b34ca192e69b258
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/179848
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/5014
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins)

src/soc/intel/baytrail/baytrail/device_nvs.h

@@ -17,8 +17,14 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#ifndef _BAYTRAIL_DEVICE_NVS_H_
+#define _BAYTRAIL_DEVICE_NVS_H_
+
 #include <stdint.h>
 
+/* Offset in Global NVS where this structure lives */
+#define DEVICE_NVS_OFFSET	0x1000
+
 #define LPSS_NVS_SIO_DMA1	0
 #define LPSS_NVS_I2C1		1
 #define LPSS_NVS_I2C2		2
@@ -57,3 +63,5 @@ typedef struct {
 	/* Extra */
 	u32	lpe_fw; /* LPE Firmware */
 } __attribute__((packed)) device_nvs_t;
+
+#endif