pci: msm: Use operation config read/write APIs in AER handler

AER handler is directly using raw read and write APIs to access
endpoint config space. Instead, use PCI framework provided APIs
as well as the register macros to stream line all config space
reads and writes to go through PCI read and write operation.
Also, use PCI framework APIs to find the pci device using BDF
this removes the dependency on local pci device table.

Change-Id: I5b0fa2dc6eb383d9db2dc42f026a2b6cb85b3d71
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>