vTPM: Fix Atmel timeout bug.

vTPM: Fix Atmel timeout bug.

Some versions of Atmel TPMs provide invalid values for TPM_CAP_PROP_TIS_TIMEOUT query.
Because timeouts are invalid, every other command after tpm_get_timeouts will fail.
It is a known issue and it was fixed recently in linux kernel tpm_tis.c on 2014-07-29.
This patch does not allow timeouts to be less than standard values.
I tested it on a Dell Latitude E5520 and after making the changes I was able to start vtpmmgr-stubdom.

Signed-off-by: Emil Condrea <emilcondrea@gmail.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>