ASoC: sun50i-dmic: avoid unused variable warning for sun50i_dmic_of_match

In configurations with CONFIG_OF=n, we get a harmless build warning:

sound/soc/sunxi/sun50i-dmic.c:268:34: warning: unused variable
'sun50i_dmic_of_match' [-Wunused-const-variable]

Signed-off-by: Ban Tao <fengzheng923@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/1666511085-2748-1-git-send-email-fengzheng923@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>