Restore the enabling of debugging by default by the DRM_DEBUG kernel option.

It remains controlled by hw.dri.*.debug no matter what.

PR:		kern/85479
Submitted by:	Oliver Fromme <olli@secnetix.de>

sys/dev/drm/drm_drv.c

@@ -38,7 +38,11 @@ __FBSDID("$FreeBSD$");
 #include "dev/drm/drm.h"
 #include "dev/drm/drm_sarea.h"
 
+#ifdef DRM_DEBUG_DEFAULT_ON
+int drm_debug_flag = 1;
+#else
 int drm_debug_flag = 0;
+#endif
 
 static int drm_load(drm_device_t *dev);
 static void drm_unload(drm_device_t *dev);