mmc: sdhci-acpi: Use the new soc_intel_is_byt() helper

Use the new soc_intel_is_byt() helper function from
include/linux/platform_data/x86/soc.h .

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>