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>

src/console/usbdebug_console.c

@@ -50,15 +50,7 @@ unsigned get_ehci_debug(void)
 
 static void dbgp_init(void)
 {
-	struct ehci_debug_info *dbg_infox;
-
-	/* At this point, all we have to do is copy the fixed address
-	 * debug_info data structure to our version defined above. */
-
-	dbg_infox = (struct ehci_debug_info *)
-		((CONFIG_RAMTOP) - sizeof(struct ehci_debug_info));
-
-	memcpy(&dbg_info, dbg_infox, sizeof(struct ehci_debug_info));
+	usbdebug_init(CONFIG_EHCI_BAR, CONFIG_EHCI_DEBUG_OFFSET, &dbg_info);
 }
 
 static void dbgp_tx_byte(unsigned char data)