test: Correct dependencies for SPL_UNIT_TEST

As exposed by "make randconfig", we have an issue with the dependencies
for SPL_UNIT_TEST. In order to test SPL_DM_DEVICE_REMOVE we also need to
have ensured that SPL_DM is enabled, so select that as well.

Signed-off-by: Tom Rini <trini@konsulko.com>

test/Kconfig

@@ -15,6 +15,7 @@ config SPL_UNIT_TEST
 	bool "Unit tests in SPL"
 	depends on SPL
 	# We need to be able to unbind devices for tests to work
+	select SPL_DM
 	select SPL_DM_DEVICE_REMOVE
 	help
 	  Select this to enable unit tests in SPL. Most test are designed for