sandbox: Enable FIT best-match

Enable this feature so that it can be tested on sandbox.

Update the vboot FDT to avoid having it match on conf-1 instead of
conf-1

Signed-off-by: Simon Glass <sjg@chromium.org>

boot/Kconfig

@@ -130,6 +130,7 @@ config FIT_VERBOSE
 
 config FIT_BEST_MATCH
 	bool "Select the best match for the kernel device tree"
+	default y if SANDBOX
 	help
 	  When no configuration is explicitly selected, default to the
 	  one whose fdt's compatibility field best matches that of

test/py/tests/vboot/sandbox-kernel.dts

@@ -2,6 +2,5 @@
 
 / {
 	model = "Sandbox Verified Boot Test";
-	compatible = "sandbox";
-
+	compatible = "none";
 };