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 <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/Kconfig

···
 
 	  If in doubt, say "N".
 
+config DRM_EXPORT_FOR_TESTS
+	bool
+
 config DRM_DEBUG_SELFTEST
 	tristate "kselftests for DRM"
 	depends on DRM
···
 	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

···
  * 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)