ASoC: codecs: rk3308: fix building without CONFIG_OF

The newly added codec has an extraneous of_match_ptr() annotation for
the ID table:

sound/soc/codecs/rk3308_codec.c:956:34: error: 'rk3308_codec_of_match' defined but not used [-Werror=unused-const-variable=]
956 | static const struct of_device_id rk3308_codec_of_match[] = {

Remove it to avoid introducing a warning when -Wunused-const-variable
gets enabled by default:

Fixes: 4ed0915f5bc4 ("ASoC: codecs: Add RK3308 internal audio codec driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://msgid.link/r/20240404095755.650364-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

ASoC: codecs: rk3308: fix "defined but not used" warning on !OF

Building with CONFIG_OF=n triggers:

warning: 'rk3308_codec_of_match' defined but not used [-Wunused-const-variable=]
warning: unused variable 'rk3308_codec_of_match' [-Wunused-const-variable]

Even though OF is needed for probing, fix by declaring as __maybe_unused to
still allow building on non-OF configurations for build testing.

Fixes: 9fdd7b45da18 ("arm64: defconfig: enable Rockchip RK3308 internal audio codec driver")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403271905.BYbGJiPi-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202403271907.0z0uuG5I-lkp@intel.com/
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://msgid.link/r/20240403-rk3308-audio-codec-fix-warning-v2-1-816bae4c1dc5@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>

ASoC: codecs: Add RK3308 internal audio codec driver

Add driver for the internal audio codec of the Rockchip RK3308 SoC.

Initially based on the vendor kernel driver [0], with lots of cleanups,
fixes, improvements, conversion to DAPM and removal of some features.

[0] https://github.com/rockchip-linux/kernel/blob/develop-4.19/sound/soc/codecs/rk3308_codec.c

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://msgid.link/r/20240305-rk3308-audio-codec-v4-4-312acdbe628f@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>