command: Fix handling of buffer passing in args[] on 64bit mcu

If the buffer pointer can't fit in a uint32_t then pass a relative
buffer offset instead.  This fixes buffer handling on 64bit linux
mcus.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/simulator/serial.c

@@ -19,6 +19,12 @@ serial_init(void)
 }
 DECL_INIT(serial_init);
 
+void *
+console_receive_buffer(void)
+{
+    return NULL;
+}
+
 static void
 do_uart(void)
 {