sandbox: add a sandbox timer and basic test

Add a sandbox timer which get time from host os and a basic
test.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index ae5b9d1..0b1b41c 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -53,6 +53,8 @@
 CONFIG_SOUND=y
 CONFIG_SOUND_SANDBOX=y
 CONFIG_SANDBOX_SPI=y
+CONFIG_TIMER=y
+CONFIG_SANDBOX_TIMER=y
 CONFIG_TPM_TIS_SANDBOX=y
 CONFIG_USB=y
 CONFIG_DM_USB=y