libcamera: rpi: Add missing SPDX headers

Multiple files in the Raspberry Pi pipeline handler and IPA module are
missing SPDX headers. Add them with the following licenses:

- For code and documentation, use the BSD-2-Clause license, as for the
  rest of the Raspberry Pi code.

- For the example pipeline handler configuration files, use the CC0-1.0
  license to facilitate their usage.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>

src/ipa/rpi/controller/decompand_status.h

@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
 #pragma once
 
 #include "libipa/pwl.h"

src/ipa/rpi/controller/rpi/decompand.cpp

@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
 #include "decompand.h"
 
 #include <libcamera/base/log.h>

src/ipa/rpi/controller/rpi/decompand.h

@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
 #pragma once
 
 #include <libipa/pwl.h>