usbdebug: Change debug port scanning

On AMD platforms, setting of USBDEBUG_DEFAULT_PORT=0 tries to scan
all physical ports one after other in incrementing order. To avoid
possible problems with other USB devices, one can select the port
number here and bypass the scan.

Intel platforms can communicate with usbdebug dongle on one
physical port only, and this option makes no difference there.

Change-Id: I45be6cc3aa91b74650eda2d444c9fcad39d58897
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3872
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/southbridge/amd/sb700/enable_usbdebug.c

@@ -58,9 +58,4 @@ void enable_usbdebug(unsigned int port)
 	/* Enable access to the EHCI memory space registers. */
 	pci_write_config8(dev, PCI_COMMAND, PCI_COMMAND_MEMORY);
 
-	/*
-	* Select the requested physical USB port (1-15) as the Debug Port.
-	* Must be called after the EHCI BAR has been set up (see above).
-	*/
-	set_debug_port(port);
 }