gazell: Add Gazell subsystem

Add Gazell Link Layer glue and Gazell Pairing library.

Signed-off-by: Bernard Lee <bernard.lee@nordicsemi.no>

Author: leewkb4567

CODEOWNERS

@@ -151,6 +151,7 @@ Kconfig*                                  @tejlmand
 /subsys/esb/                              @Raane @lemrey
 /subsys/event_manager/                    @pdunaj
 /subsys/fw_info/                          @hakonfam
+/subsys/gazell/                           @leewkb4567
 /subsys/mpsl/                             @rugeGerritsen
 /subsys/net/                              @rlubos
 /subsys/net/lib/azure_*                   @jtguggedal @simensrostad @coderbyheart

include/gzll_glue.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#ifndef __GZLL_GLUE_H
+#define __GZLL_GLUE_H
+
+/**
+ * @file
+ * @brief Gazell Link Layer glue
+ *
+ * File defines a set of functions and variables called by Gazell Link Layer.
+ */
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup gzll_glue Gazell Link Layer glue
+ *
+ * File defines a set of functions and variables called by Gazell Link Layer.
+ *
+ * @{
+ */
+
+/**
+ * @brief Gazell Link Layer glue initialization.
+ *
+ * @retval true  if initialization is successful.
+ * @retval false if initialization is unsuccessful.
+ */
+bool gzll_glue_init(void);
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __GZLL_GLUE_H */