drm: Move EXPORT_SYMBOL_FOR_TESTS_ONLY under a separate Kconfig

Currently, we only export symbols for drm-selftests which are either
compiled as modules or into the main drm builtin. However, if we want to
export symbols from drm.ko for the drivers' selftests, we require a
means of controlling that export separately. So we add a new Kconfig to
determine whether or not the EXPORT_SYMBOL_FOR_TESTS_ONLY() takes
effect.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20191107180601.30815-1-chris@chris-wilson.co.uk

drivers/gpu/drm/Kconfig

@@ -54,6 +54,9 @@ config DRM_DEBUG_MM
 
 	  If in doubt, say "N".
 
+config DRM_EXPORT_FOR_TESTS
+	bool
+
 config DRM_DEBUG_SELFTEST
 	tristate "kselftests for DRM"
 	depends on DRM
@@ -61,6 +64,7 @@ config DRM_DEBUG_SELFTEST
 	select PRIME_NUMBERS
 	select DRM_LIB_RANDOM
 	select DRM_KMS_HELPER
+	select DRM_EXPORT_FOR_TESTS if m
 	default n
 	help
 	  This option provides kernel modules that can be used to run

include/drm/drm_util.h

@@ -41,7 +41,7 @@
  * Use EXPORT_SYMBOL_FOR_TESTS_ONLY() for functions that shall
  * only be visible for drmselftests.
  */
-#if defined(CONFIG_DRM_DEBUG_SELFTEST_MODULE)
+#if defined(CONFIG_DRM_EXPORT_FOR_TESTS)
 #define EXPORT_SYMBOL_FOR_TESTS_ONLY(x) EXPORT_SYMBOL(x)
 #else
 #define EXPORT_SYMBOL_FOR_TESTS_ONLY(x)