mmc: dw_mmc-pci: convert to use pcim_* and devm_*

The PCI driver is getting simplier and tidier with pcim_* and devm_*
functions in use.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>