vboot: remove unused 2nvstorage_fields.h from vb2_api.h

2nvstorage_fields.h is no longer needed for
NEED_VB20_INTERNALS users.  Remove it.

The only headers left are 2misc.h (for vb2_get_sd() in
coreboot) and 2struct.h (for VBSD->vb2_shared_data
conversion in depthcharge).

BUG=b:124141368, chromium:956474
TEST=make clean && make runtests
TEST=Check that coreboot and depthcharge compile
BRANCH=none

Change-Id: I389b4f2828dca2934c5036df9dbfca03dc651bfa
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1971112
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
Tested-by: Joel Kitching <kitching@chromium.org>
diff --git a/firmware/include/vb2_api.h b/firmware/include/vb2_api.h
index 0411312..0dfc3dd 100644
--- a/firmware/include/vb2_api.h
+++ b/firmware/include/vb2_api.h
@@ -33,9 +33,8 @@
  * TODO: Make cleaner APIs to this stuff.
  */
 #ifdef NEED_VB20_INTERNALS
-#include "../2lib/include/2misc.h"  /* for vb2_get_sd */
-#include "../2lib/include/2nvstorage_fields.h"
-#include "../2lib/include/2struct.h"
+#include "../2lib/include/2misc.h"  /* for vb2_get_sd() */
+#include "../2lib/include/2struct.h"  /* for vb2_shared_data struct */
 #endif
 
 #endif  /* VBOOT_REFERENCE_VB2_API_H_ */