usb/xhci: update a comment regarding the BOS descriptor to reflect the code

The comment is a quote of Alan Stern and reflects the data structure
better than the the initial comment.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/host/xhci-hub.c

@@ -29,7 +29,7 @@
 #define	PORT_RWC_BITS	(PORT_CSC | PORT_PEC | PORT_WRC | PORT_OCC | \
 			 PORT_RC | PORT_PLC | PORT_PE)
 
-/* usb 1.1 root hub device descriptor */
+/* USB 3.0 BOS descriptor and a capability descriptor, combined */
 static u8 usb_bos_descriptor [] = {
 	USB_DT_BOS_SIZE,		/*  __u8 bLength, 5 bytes */
 	USB_DT_BOS,			/*  __u8 bDescriptorType */