kernel: Don't watch the "dev" legacy driver directory.

We don't watch its children, and most drivers within it are within
subdirectories. Further, all drivers in it are really symlinks to "bin",
which we also watch. So there is really not much purpose in watching
"dev" directly.

Should fix #4638.

src/system/kernel/device_manager/legacy_drivers.cpp

@@ -1488,7 +1488,6 @@ legacy_driver_probe(const char* subPath)
 				path.UnlockBuffer();
 				path.Append("kernel/drivers");
 
-				start_watching(path.Path(), "dev");
 				start_watching(path.Path(), "bin");
 			} else
 				path.UnlockBuffer();