ASoC: Intel: bytcr_rt5651: Remove is_valleyview helper

Remove is_valleyview helper, this is not necessary, we can simply call
x86_match_cpu() directly instead.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>