ipq806x: add pcie support to ipq806x based platforms

This change adds PCIe support to IPQ806x based platforms. The driver is
actually cherry-picked from the following LKML thread:
*https://lwn.net/Articles/643086/

 (patches 110-111)

We also add here an additional fix to support multiple PCI controllers
on the same platform (patch 112), and to patch the ap148 & dbs149 DTS
files (patch 113).

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>

SVN-Revision: 45663