i2c: designware-pci: remove Moorestown support

The Moorestown support bits were removed few years ago. This is a follow up to
that changes.

Suggested-by: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>