ASoC: sunxi: sun4i-spdif: Fix misspelling of 'reg_dac_txdata' in kernel-doc

ASoC: sunxi: sun4i-spdif: Fix misspelling of 'reg_dac_txdata' in kernel-doc

Property name descriptions need to match exactly.

Fixes the following W=1 kernel build warning(s):

sound/soc/sunxi/sun4i-spdif.c:178: warning: Function parameter or
member 'reg_dac_txdata' not described in 'sun4i_spdif_quirks'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Andrea Venturi <be17068@iperbole.bo.it>
Cc: Marcus Cooper <codekipper@gmail.com>
Link: https://lore.kernel.org/r/20200709162328.259586-5-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>