USB: gadget: udc: Remove some dead code

The 'drd_wq' workqueue_struct has never been used.
It is only destroyed, but never created.

It was introduced in commit 1b9f35ad ("usb: gadget: udc: Add Synopsys
UDC Platform driver")

Remove the corresponding dead code and save some space from the 'udc'
structure.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/9a85b2353843b95e2d86acb3103967fd405a8536.1633865503.git.christophe.jaillet@wanadoo.frSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/amd5536udc.h

@@ -572,7 +572,6 @@ struct udc {
 	struct extcon_specific_cable_nb	extcon_nb;
 	struct notifier_block		nb;
 	struct delayed_work		drd_work;
-	struct workqueue_struct		*drd_wq;
 	u32				conn_type;
 };
 

drivers/usb/gadget/udc/snps_udc_plat.c

@@ -243,11 +243,6 @@ static int udc_plat_remove(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, NULL);
 
-	if (dev->drd_wq) {
-		flush_workqueue(dev->drd_wq);
-		destroy_workqueue(dev->drd_wq);
-	}
-
 	phy_power_off(dev->udc_phy);
 	phy_exit(dev->udc_phy);
 	extcon_unregister_notifier(dev->edev, EXTCON_USB, &dev->nb);