HAL: AAR: Add missing copyright and license

This file was contributed in
d6ecc00

But the license and copyright header was missing.

The contribution was properly signed off, and therefore
properly licensed.
But for clarity and consistency let's add the header
to the file.

The code itself is mostly a copy of content with from
another file with Copyright (c) 2017 Oticon A/S with minor
changes from Nordic, therefore add both copyrights to it

Signed-off-by: Alberto Escolar Piedras <[email protected]>

Author: aescolar

src/nrfx/hal/nrf_aar.c

@@ -1,3 +1,11 @@
+/*
+ * Copyright (c) 2020 Oticon A/S
+ * Copyright (c) 2020 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Note that the function prototypes are taken from the NRFx HAL
+ */
 #include "nrf_aar.h"
 #include "bs_tracing.h"
 #include "NRF_AAR.h"