ASoC: Intel: sof_rt5682: Fix uninitialized variable in probe

Initialize "is_legacy_cpu" to false to prevent an uninitialized variable
bug.

Fixes: 8efcd486 ("ASoC: Intel: sof_rt5682: use common module for sof_card_private initialization")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://msgid.link/r/6e16433f-1897-46a2-b3ee-e177e7d846b8@moroto.mountain


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