ASoC: rt286: Fix upper byte in DMIC2 configuration

This HDA verb sets the upper byte of the Configuration Default register, so
only an 8-bit value should be used. For the rt298, the same fix was applied
in commit f8f2dc4a

 ("ASoC: rt298: fix wrong setting of gpio2_en").

Signed-off-by: David Ward <david.ward@gatech.edu>
Link: https://lore.kernel.org/r/20210418134658.4333-2-david.ward@gatech.edu
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>