test/boot: Make BOOTSTD tests depend on UT_BOOTSTD

While we have a symbol for controlling if we will be testing BOOTSTD or
not, and it depends on SANDBOX, we do not control the building of
test/boot/ content correctly. Guard the current bootstd tests with
a check for UT_BOOTSTD and leave the measurement test available.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/test/boot/Makefile b/test/boot/Makefile
index 8ec5daa..d8eded2 100644
--- a/test/boot/Makefile
+++ b/test/boot/Makefile
@@ -2,12 +2,15 @@
 #
 # Copyright 2021 Google LLC
 
+ifdef CONFIG_UT_BOOTSTD
 obj-$(CONFIG_BOOTSTD) += bootdev.o bootstd_common.o bootflow.o bootmeth.o
 obj-$(CONFIG_FIT) += image.o
-obj-$(CONFIG_MEASURED_BOOT) += measurement.o
 
 obj-$(CONFIG_EXPO) += expo.o
 obj-$(CONFIG_CEDIT) += cedit.o
+endif
+
+obj-$(CONFIG_MEASURED_BOOT) += measurement.o
 
 ifdef CONFIG_OF_LIVE
 obj-$(CONFIG_BOOTMETH_VBE_SIMPLE) += vbe_simple.o