ACPI / LPSS: Call pwm_add_table() for Bay Trail PWM device

On Bay Trail systems with a Crystal Cove PMIC the Crystal Cove's PWM is
used to control the backlight brightness. On systems without one, the
Crystal Cove SoC's PWM is used and we need to call pwm_add_table() so
that the i915 driver can find the pwm for controlling the backlight.

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