lib/cbfs: Use linker symbols over .c include in cbfs.c

Change-Id: Ieb7f383c84401aab87adc833deebf289cd0c9a0f
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/7426
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>

src/lib/cbfs_core.c

@@ -52,6 +52,8 @@
 #include <cbfs.h>
 #include <string.h>
 
+#include "cbfs_core.h"
+
 /* returns a pointer to CBFS master header, or CBFS_HEADER_INVALID_ADDRESS
  *  on failure */
 const struct cbfs_header *cbfs_get_header(struct cbfs_media *media)