tpm2: ftpm: open session with privileged ree login

Opens the fTPM session with TEE_LOGIN_REE_KERNEL as fTPM may restrict
access to that login when Linux based OS is running as applications are
expected to got through the Linux TPMv2 driver.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>