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<christophe-h.ricard@st.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 2600bf7..4034a2e 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -12,6 +12,7 @@
 CONFIG_CMD_PMIC=y
 CONFIG_CMD_REGULATOR=y
 CONFIG_CMD_TPM=y
+CONFIG_CMD_TPM_TEST=y
 CONFIG_OF_CONTROL=y
 CONFIG_OF_HOSTFILE=y
 CONFIG_CLK=y