ARM: dts: msm: Add PD PHY peripheral to pmi8998 on sdm845

Add device node for the USB PD PHY peripheral found in PMI8998.
Also reference the phandle to this device as the extcon for the
usb0 node on SDM845 as it will act to notify when the USB cable
is attached.

Change-Id: I42916b13e5d28dd3f3b0ed40c53767cbd7ae32b1
Signed-off-by: Jack Pham <jackp@codeaurora.org>