NTB: Add support for AMD PCI-Express Non-Transparent Bridge

NTB: Add support for AMD PCI-Express Non-Transparent Bridge

BugLink: http://bugs.launchpad.net/bugs/1542071
This adds support for AMD's PCI-Express Non-Transparent Bridge
(NTB) device on the Zeppelin platform. The driver connnects to the
standard NTB sub-system interface, with modification to add hooks
for power management in a separate patch. The AMD NTB device has 3
memory windows, 16 doorbell, 16 scratch-pad registers, and supports
up to 16 PCIe lanes running a Gen3 speeds.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Reviewed-by: Allen Hubbe <Allen.Hubbe@emc.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
(cherry picked from commit a1b3695820aa490e58915d720a1438069813008b)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>