Advertise number of chip selects via property for Intel Braswell.

Fixes: 620c803f ("ACPI: LPSS: Provide an SSP type to the driver")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>