usb: gadget: composite: enable BESL support

According to USB 2.0 ECN Errata for Link Power
Management (USB2-LPM-Errata-final.pdf), BESL
must be enabled if LPM is enabled.

This helps with USB30CV TD 9.21 LPM L1
Suspend Resume Test.
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/composite.c

@@ -560,7 +560,7 @@ static int bos_desc(struct usb_composite_dev *cdev)
 	usb_ext->bLength = USB_DT_USB_EXT_CAP_SIZE;
 	usb_ext->bDescriptorType = USB_DT_DEVICE_CAPABILITY;
 	usb_ext->bDevCapabilityType = USB_CAP_TYPE_EXT;
-	usb_ext->bmAttributes = cpu_to_le32(USB_LPM_SUPPORT);
+	usb_ext->bmAttributes = cpu_to_le32(USB_LPM_SUPPORT | USB_BESL_SUPPORT);
 
 	/*
 	 * The Superspeed USB Capability descriptor shall be implemented by all