tpm: Enable 'tpmtest' command for Chrome OS boards with TPMs

This command provides a few useful tests so enable it for common boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Christophe <Ricard&lt;christophe-h.ricard@st.com>
Reviewed-by: Heiko Schocher <hs@denx.de>