usb: pd: Add DP lane number notification

Add DP lane number notification which can be used in the
case that need to know DP lane number.

Change-Id: Iec66cbf6a34ca6c4346fa93f7706f3aff9f6a775
Signed-off-by: Liangliang Lu <luliang@codeaurora.org>
3 files changed