configs: enable CMD_TPM on QEMU ARM

With TPM emulation enabled in u-boot-test-hooks we should also provide the
tpm2 command used for the test/py/tests/test_tpm2.py test.

One of the Python TPMv2 tests expects sandbox specific values. So disable
it on other platforms.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>