QEMU debugcon: Move under drivers/emulation/qemu

Also prepare this console for use in romstage.

Change-Id: I26a4d4b5db1e44a261396a21bb0f0574d72aa86d
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5136
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>

src/include/console/qemu_debugcon.h

@@ -0,0 +1,7 @@
+#ifndef _QEMU_DEBUGCON_H_
+#define _QEMU_DEBUGCON_H_
+
+void qemu_debugcon_init(void);
+void qemu_debugcon_tx_byte(unsigned char data);
+
+#endif