tpm: Add reserved memory event log

Some platforms may desire to pass the event log up to Linux in the
form of a reserved memory region. In particular, this is desirable
for embedded systems or baseboard management controllers (BMCs)
booting with U-Boot. IBM OpenBMC BMCs will be the first user.
Add support for the reserved memory in the TPM core to find the
region and map it.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
[jarkko: removed spurious dev_info()'s from tpm_read_log_memory_region()]
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
[yang: return -ENOMEM when devm_memremap() fails]
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>