pci: fix some warnings related to assumptions about

The following commit introduced some warnings associated with using
pci_addr_t instead of a proper 32-bit data type.

commit af778c6d
Author: Andrew Sharp <andywyse6@gmail.com>
Date:   Wed Aug 1 12:27:16 2012 +0000

    pci: fix errant data types and corresponding access functions

On some platforms pci_addr_t is defined as a 64-bit data type so its not
proper to use with pci_{read,write}_config_dword.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>