drm/mm: Allow CONFIG_DRM_MM_DEBUG with DRM=m

The original rationale for
commit cd456f8 ("drm: Restrict stackdepot usage to builtin drm.ko")
was that depot_save_stack() (which is what we used back then)
wasn't exported. stack_depot_save() (which is what we use now) is
exported however, so relax the dependency allow CONFIG_DRM_MM_DEBUG
with DRM=m.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231215111129.9559-1-ville.syrjala@linux.intel.com
Acked-by: Javier Martinez Canillas <javierm@redhat.com>

drivers/gpu/drm/Kconfig

@@ -42,7 +42,7 @@ config DRM_MIPI_DSI
 config DRM_DEBUG_MM
 	bool "Insert extra checks and debug info into the DRM range managers"
 	default n
-	depends on DRM=y
+	depends on DRM
 	depends on STACKTRACE_SUPPORT
 	select STACKDEPOT
 	help