meson: console: Add missing define to fix build

It isn't possible to build this driver without adding this define.

Change-Id: Iba2ced411cd8ce438787871fa01b414d32b9aa42
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

drivers/meson/console/aarch64/meson_console.S

@@ -6,6 +6,7 @@
 
 #include <asm_macros.S>
 #include <assert_macros.S>
+#define USE_FINISH_CONSOLE_REG_2
 #include <console_macros.S>
 #include <meson_console.h>