pwm: lpss: Split Tangier configuration

As a preparation for special treatment for Broxton we split Tangier
configuration.

Fixes: b89b4b7a ("pwm: lpss: pci: Enable PWM module on Intel Edison")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>