ASoC: rt715: add vendor clear control register

Add vendor clear control register in readable register's
callback function. This prevents an access failure reported
in Intel CI tests.

Signed-off-by: Jack Yu <jack.yu@realtek.com>
Closes: https://github.com/thesofproject/linux/issues/4860


Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/6a103ce9134d49d8b3941172c87a7bd4@realtek.com


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