tpm: lookup cancel path under tpm device class

tpm: lookup cancel path under tpm device class

Since Linux commit 313d21eeab9282e, tpm devices have their own device
class "tpm" and the cancel path must be looked up under
/sys/class/tpm/ instead of /sys/class/misc/.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
(cherry picked from commit 05b71fb207ab7f016e067bd2a40fc0804362eb74)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>