tcgbios: Disable platform hierarchy in case of failure

In the rare case of a TPM 2 failure, disable the platform hierarchy after
disabling the endorsement and owner hierarchies.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
diff --git a/src/tcgbios.c b/src/tcgbios.c
index 02921d8..31f4d7b 100644
--- a/src/tcgbios.c
+++ b/src/tcgbios.c
@@ -983,6 +983,7 @@
     case TPM_VERSION_2:
         tpm20_hierarchycontrol(TPM2_RH_ENDORSEMENT, TPM2_NO);
         tpm20_hierarchycontrol(TPM2_RH_OWNER, TPM2_NO);
+        tpm20_hierarchycontrol(TPM2_RH_PLATFORM, TPM2_NO);
         break;
     }