fw: simplify how to enable QEMU debug in firmware.

- Remove the define `NOCONSOLE`, add define `QEMU_CONSOLE`
- Inverse the use of it, add the define to have QEMU debug output in fw.
- Add a make target `qemu_firmware.elf` which builds the firmware with
  QEMU console enabled.

Co-authored-by: Mikael Ågren <mikael@tillitis.se>

hw/application_fpga/fw/tk1/lib.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022 - Tillitis AB
+ * Copyright (C) 2022-2024 - Tillitis AB
  * SPDX-License-Identifier: GPL-2.0-only
  */
 
@@ -7,7 +7,7 @@
 #include "assert.h"
 #include "types.h"
 
-#ifndef NOCONSOLE
+#ifdef QEMU_CONSOLE
 struct {
 	uint32_t arr[2];
 } static volatile tohost __attribute__((section(".htif")));