msm: ep_pcie: add PCIe endpoint driver snapshot

Snapshot of PCIe endpoint driver as of msm-4.14.

'commit <adeff59> (""drivers: clk: msm:
fix compilation for non DEBUG_FS build"")'.

The following changes were done:
-Replace msm_bus driver with interconnect framework.
-Remove iommu deprecated API's.
-Fix checkpatch warnings on usage of module param.
-Fix several checkpatch warnings.

Change-Id: I04ee8f5d5802af0aa0cdd607a79c91e3eca7f194
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>