i2c: designware: Get rid of PCI driver specifics in common code

Do not spread PCI specifics over common code. It seems to be a layering
violation which can be easily avoided. Refactor PCI driver and drop
PCI specifics from common code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>