vboot: Stop creating backup space in TPM

There is no code which uses the backup space in TPM created for vboot
nvram.

All chromebooks currently supported at the trunk store vboot nvram
in flash directly or as a backup.

BUG=chrome-os-partner:47915
BRANCH=none
TEST=emerge-samus coreboot

Change-Id: I9445dfd822826d668b3bfed8ca50dc9386f2b2b0
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 5cee2d54c96ad7952af2a2c1f773ba09c5248f41
Original-Change-Id: Ied0cec0ed489df3b39f6b9afd3941f804557944f
Original-Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/395507
Original-Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://review.coreboot.org/16997
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/src/include/antirollback.h b/src/include/antirollback.h
index f088ee2..889ba9a 100644
--- a/src/include/antirollback.h
+++ b/src/include/antirollback.h
@@ -17,8 +17,8 @@
 /* TPM NVRAM location indices. */
 #define FIRMWARE_NV_INDEX               0x1007
 #define KERNEL_NV_INDEX                 0x1008
-/* This is just an opaque space for backup purposes */
-#define BACKUP_NV_INDEX                 0x1009
+/* 0x1009 used to be used as a backup space. Think of conflicts if you
+ * want to use 0x1009 for something else. */
 
 /* Structure definitions for TPM spaces */
 
diff --git a/src/vboot/secdata_tpm.c b/src/vboot/secdata_tpm.c
index 76b90ab..b1f3197 100644
--- a/src/vboot/secdata_tpm.c
+++ b/src/vboot/secdata_tpm.c
@@ -245,11 +245,6 @@
 	VBDEBUG("TPM: Clearing owner\n");
 	RETURN_ON_FAILURE(tpm_clear_and_reenable());
 
-	/* Define the backup space. No need to initialize it, though. */
-	RETURN_ON_FAILURE(safe_define_space(BACKUP_NV_INDEX,
-					    TPM_NV_PER_PPWRITE,
-					    VB2_NVDATA_SIZE));
-
 	/* Define and initialize the kernel space */
 	RETURN_ON_FAILURE(safe_define_space(KERNEL_NV_INDEX,
 					    TPM_NV_PER_PPWRITE,