tpm: create TPM 2.0 devices using own device class

Added own class for TPM devices that is used for TPM 2.0 and onwards.
Each struct tpm_chip has its own struct device instance belonging to
this class, which has a character device for communication with the
user space.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
tpm: fix: export tpm2_gen_interrupt()

EXPORT_SYMBOL_GPL() was missing for tpm2_gen_interrupt().

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