sb/intel/common: Properly guard USB debug

The declarations in usb_debug.c needs to be guarded in order to not
conflict with other chipsets.

Change-Id: I84c3401b9419f2878c2cfdf81147fa854018f9ae
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36878
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Mike Banon <mikebdp2@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/southbridge/intel/ibexpeak/Kconfig

@@ -22,7 +22,6 @@ config SOUTH_BRIDGE_OPTIONS # dummy
 	def_bool y
 	select ACPI_INTEL_HARDWARE_SLEEP_VALUES
 	select IOAPIC
-	select HAVE_USBDEBUG
 	select HAVE_SMI_HANDLER
 	select USE_WATCHDOG_ON_BOOT
 	select PCIEXP_ASPM
@@ -45,6 +44,7 @@ config SOUTH_BRIDGE_OPTIONS # dummy
 	select HAVE_POWER_STATE_AFTER_FAILURE
 	select HAVE_POWER_STATE_PREVIOUS_AFTER_FAILURE
 	select SOUTHBRIDGE_INTEL_COMMON_WATCHDOG
+	select SOUTHBRIDGE_INTEL_COMMON_USB_DEBUG
 
 config EHCI_BAR
 	hex