usb: pd: add snapshot of qpnp-pdphy and policy_engine drivers

The qpnp-pdphy driver provides support for the PD PHY peripheral
found on Qualcomm Technologies, Inc. PMICs. This along with
the policy engine provides a protocol stack that supports
USB Power Delivery communication over a Type-C port.

This snapshot is taken as of msm-4.9 commit 11273b09e247
("usb: phy: msm: Remove phy-msm-usb driver"). This includes one
minor fixup to remove use of the extcon mutually_exclusive
field which is no longer visible outside of drivers/extcon.

Change-Id: I0a34076dee8476494dfccfe6fc807247caab8927
Signed-off-by: Jack Pham <jackp@codeaurora.org>