greybus: eliminate unneeded null check

Coccinelle points out that debugfs_remove_recursive() handles a null
argument properly, so there's no need to check for NULL before
making the call.  I have verified this is true of the kernel we're
now working with (arche-6.0).
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/camera.c

@@ -883,8 +883,7 @@ static int gb_camera_debugfs_init(struct gb_camera *gcam)
 
 static void gb_camera_debugfs_cleanup(struct gb_camera *gcam)
 {
-	if (gcam->debugfs.root)
-		debugfs_remove_recursive(gcam->debugfs.root);
+	debugfs_remove_recursive(gcam->debugfs.root);
 
 	vfree(gcam->debugfs.buffers);
 }