cros_ec: sandbox: Add Chrome OS EC emulation

Add a simple emulation of the Chrome OS EC for sandbox, so that it can
perform various EC tasks such as keyboard handling.

Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

include/fdtdec.h

@@ -88,6 +88,7 @@ enum fdt_compat_id {
 	COMPAT_INFINEON_SLB9635_TPM,	/* Infineon SLB9635 TPM */
 	COMPAT_INFINEON_SLB9645_TPM,	/* Infineon SLB9645 TPM */
 	COMPAT_SAMSUNG_EXYNOS5_I2C,	/* Exynos5 High Speed I2C Controller */
+	COMPAT_SANDBOX_HOST_EMULATION,	/* Sandbox emulation of a function */
 
 	COMPAT_COUNT,
 };