tpm: Driver for TPM 2.0 CRB Interface

tpm_crb is a driver for TPM 2.0 CRB Interface as defined in

- http://www.trustedcomputinggroup.org/resources/tpm_20_mobile_command_response_buffer_interface_specification
- http://www.trustedcomputinggroup.org/resources/server_acpi_specification

Tested with TPM2 PTT included in 4th generation Intel processors.

Notes:

- PTT reports using only ACPI start as start method but seems to
  require CRB with ACPI start.
- cmdReady does not seem to work with PTT.
- Does not have yet interrupt based send/receive because I don't
  have hardware for that.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
tpm: TPM2 sysfs attributes

Added tpm2-sysfs.c that implements sysfs attributes for a TPM2
device.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>