tpm: call tpm_chip_unregister() last in tpm_tis_chip_remove()

API was not used right in tpm_tis_chip_remove(). Vendor specific
stuff must be done first and as a last step tpm_chip_unregister()
call is needed. Releasing the struct tpm_chip instance should not
be done from the device driver.

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