test: spl: Fix spl_test_load not failing if fname doesn't exist

Returning a negative value from a unit test doesn't automatically fail the
test.  We have to fail an assertion. Modify the test to do so.

This now causes the test to count as a failure on VPL. This is because the
fname of SPL (and U-Boot) is generated with make_exec in os_jump_to_image.
The original name of SPL is gone, and we can't determine the name of U-Boot
from the generated name.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sandbox_vpl_defconfig b/configs/sandbox_vpl_defconfig
index 8d76f19..5bd0281 100644
--- a/configs/sandbox_vpl_defconfig
+++ b/configs/sandbox_vpl_defconfig
@@ -262,3 +262,4 @@
 CONFIG_SPL_UNIT_TEST=y
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
+# CONFIG_SPL_UT_LOAD_OS is not set
diff --git a/test/image/spl_load_os.c b/test/image/spl_load_os.c
index bf374f2..3b2967d 100644
--- a/test/image/spl_load_os.c
+++ b/test/image/spl_load_os.c
@@ -58,10 +58,8 @@
 	load.read = read_fit_image;
 
 	ret = sandbox_find_next_phase(fname, sizeof(fname), true);
-	if (ret) {
-		printf("(%s not found, error %d)\n", fname, ret);
-		return ret;
-	}
+	if (ret)
+		ut_assertf(0, "%s not found, error %d\n", fname, ret);
 	load.filename = fname;
 
 	header = spl_get_load_buffer(-sizeof(*header), sizeof(*header));