This patch addresses BZ 1244895.

Adapt the sysfs TPM command cancel path for the TPM driver that
does not use a miscdevice anymore since Linux 4.0. Support old
and new paths and check their availability.

Add a mockup for the test cases to avoid the testing for
availability of the cancel path.
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>