drivers: usb: early: remove unused code

Remove this line of code because devnum is overwritten before it can be used.
This could happen if line of code 609 (goto try_again;) is executed. Otherwise,
devnum is never used again.

Addresses-Coverity-ID: 1226870
Signed-off-by: NGustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/early/ehci-dbgp.c

@@ -580,7 +580,6 @@ static int _dbgp_external_startup(void)
 				USB_DEBUG_DEVNUM);
 			goto err;
 		}
-		devnum = USB_DEBUG_DEVNUM;
 		dbgp_printk("debug device renamed to 127\n");
 	}