Fix usb debug dongle support

- move enable_usbdebug() declaration to usbdebug.h
- reinitialize debug driver in ramstage, as copying the data
  structure from romstage doesn't work right now. This way of copying
  data from romstage to ramstage is really board/cpu specific, and is
  likely to break often. So don't do it.

Change-Id: I394678ded6679c1803e29eb691b926182bdcab68
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/355
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/src/southbridge/sis/sis966/Makefile.inc b/src/southbridge/sis/sis966/Makefile.inc
index f796047..76dd31a 100644
--- a/src/southbridge/sis/sis966/Makefile.inc
+++ b/src/southbridge/sis/sis966/Makefile.inc
@@ -9,7 +9,10 @@
 driver-y += pcie.c
 driver-y += aza.c
 ramstage-y += reset.c
-romstage-y += enable_usbdebug.c
+
+romstage-$(CONFIG_USBDEBUG) += enable_usbdebug.c
+ramstage-$(CONFIG_USBDEBUG) += enable_usbdebug.c
+smm-$(CONFIG_USBDEBUG) += enable_usbdebug.c
 
 chipset_bootblock_inc += $(src)/southbridge/sis/sis966/romstrap.inc
 chipset_bootblock_lds += $(src)/southbridge/sis/sis966/romstrap.lds