ARM: dts: msm: Add PCIe EP device tree files for SDXPOORWILLS

Add new device tree files for SDXPOORWILLS based platforms where PCIe
EP (endpoint) mode is required for the communication with host side and
PCIe RC (root complex) mode has to be disabled.

Change-Id: I9ff9160430cb5c8fe43028eb7b67c489801d1b43
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>