tpm: Don't replay an EventLog if tcg2_log_parse() fails

tpm: Don't replay an EventLog if tcg2_log_parse() fails

We used to stop replaying an EventLog if parsing failed, but that got
lost in commit 97707f12fdab ("tpm: Support boot measurements").

When an EventLog is passed yo us from a previous bootloader, we want to
validate it as much as we can and make sure the defined PCR banks of
the log exist in our TPM and firmware so we can replay it if needed or
use it as-in, in case the PCRs are already extended.

So let's add the checks back and while at it simplify the logic of
rejecting an EventLog.

Signed-off-by: Raymond Mao <raymond.mao@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>