mfd: ab8500-debugfs: Remove unnecessary null test before debugfs_remove_recursive

Fix checkpatch warning:
WARNING: debugfs_remove_recursive(NULL) is safe this check is probably not required
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/ab8500-debugfs.c

@@ -3191,7 +3191,6 @@ static int ab8500_debug_probe(struct platform_device *plf)
 	return 0;
 
 err:
-	if (ab8500_dir)
 	debugfs_remove_recursive(ab8500_dir);
 	dev_err(&plf->dev, "failed to create debugfs entries.\n");