greybus: es1: no need to check for NULL on debugfs_remove()

The function can, and even expects NULL, so don't check.
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/es1.c

@@ -558,10 +558,8 @@ static void usb_log_enable(struct es1_ap_dev *es1, int enable)
 							gb_debugfs_get(), NULL,
 							&apb1_log_fops);
 	} else {
-		if (apb1_log_dentry) {
 		debugfs_remove(apb1_log_dentry);
 		apb1_log_dentry = NULL;
-		}
 
 		if (apb1_log_task) {
 			kthread_stop(apb1_log_task);