security/tpm: Check for NULL pointer

Change bce49c2 (security/tpm: Improve TCPA log generation) missed
checking for NULL pointer before accessing the tcpa_table returned by
tcpa_log_init. This change fixes the boot hang observed on octopus by
ensuring pointer is checked for NULL before using it.

BUG=b:111403731
TEST=Verified that octopus boots up fine.

Change-Id: I2e46197065f8db1dc028a85551546263e60d46b2
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/27933
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Justin TerAvest <teravest@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed