drm/xe/kunit: fix link failure with built-in xe

When the driver is built-in but the tests are in loadable modules,
the helpers don't actually get put into the driver:

ERROR: modpost: "xe_kunit_helper_alloc_xe_device" [drivers/gpu/drm/xe/tests/xe_test.ko] undefined!

Change the Makefile to ensure they are always part of the driver
even when the rest of the kunit tests are in loadable modules.

Fixes: 5095d13d ("drm/xe/kunit: Define helper functions to allocate fake xe device")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240226124736.1272949-1-arnd@kernel.orgSigned-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

drivers/gpu/drm/xe/Kconfig

@@ -10,6 +10,7 @@ config DRM_XE
 	select DRM_BUDDY
 	select DRM_EXEC
 	select DRM_KMS_HELPER
+	select DRM_KUNIT_TEST_HELPERS if DRM_XE_KUNIT_TEST != n
 	select DRM_PANEL
 	select DRM_SUBALLOC_HELPER
 	select DRM_DISPLAY_DP_HELPER

drivers/gpu/drm/xe/Kconfig.debug

@@ -76,7 +76,6 @@ config DRM_XE_KUNIT_TEST
 	depends on DRM_XE && KUNIT && DEBUG_FS
 	default KUNIT_ALL_TESTS
 	select DRM_EXPORT_FOR_TESTS if m
-	select DRM_KUNIT_TEST_HELPERS
 	help
 	  Choose this option to allow the driver to perform selftests under
 	  the kunit framework

drivers/gpu/drm/xe/Makefile

@@ -158,8 +158,10 @@ xe-$(CONFIG_PCI_IOV) += \
 	xe_lmtt_2l.o \
 	xe_lmtt_ml.o
 
-xe-$(CONFIG_DRM_XE_KUNIT_TEST) += \
-	tests/xe_kunit_helpers.o
+# include helpers for tests even when XE is built-in
+ifdef CONFIG_DRM_XE_KUNIT_TEST
+xe-y += tests/xe_kunit_helpers.o
+endif
 
 # i915 Display compat #defines and #includes
 subdir-ccflags-$(CONFIG_DRM_XE_DISPLAY) += \