test: dm: spi: Fix sandbox dm_test_spi_find()

Per sandbox_cs_info(), sandbox spi controller only supports chip
select 0. Current test case tries to locate devices on chip select
1, and any call to spi_get_bus_and_cs() or spi_cs_info() with cs
number 1 should not return 0.

This updates the test case to handle it correctly.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/test/dm/spi.c b/test/dm/spi.c
index ffd789c..8e417ac 100644
--- a/test/dm/spi.c
+++ b/test/dm/spi.c
@@ -77,10 +77,10 @@
 	/* We should be able to add something to another chip select */
 	ut_assertok(sandbox_sf_bind_emul(state, busnum, cs_b, bus, node,
 					 "name"));
-	ut_assertok(spi_get_bus_and_cs(busnum, cs_b, speed, mode,
+	ut_asserteq(-EINVAL, spi_get_bus_and_cs(busnum, cs_b, speed, mode,
 				       "spi_flash_std", "name", &bus, &slave));
-	ut_assertok(spi_cs_info(bus, cs_b, &info));
-	ut_asserteq_ptr(info.dev, slave->dev);
+	ut_asserteq(-EINVAL, spi_cs_info(bus, cs_b, &info));
+	ut_asserteq_ptr(NULL, info.dev);
 
 	/*
 	 * Since we are about to destroy all devices, we must tell sandbox