Add Djinn. (#17382)

* Add Djinn.

* Review comments.

* Further cleanup.

keyboards/tzarc/djinn/halconf.h

@@ -0,0 +1,14 @@
+// Copyright 2018-2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#define HAL_USE_GPT TRUE
+#define HAL_USE_PWM TRUE
+#define HAL_USE_SPI TRUE
+#define HAL_USE_SERIAL TRUE
+#define SERIAL_BUFFERS_SIZE 256
+
+// This enables interrupt-driven mode
+#define PAL_USE_WAIT TRUE
+
+#include_next <halconf.h>