drm/msm/dp: listen to USB events to terminate simulation

In case USB cable is removed while DP simulation is running,
as USB may re-program PHY, DP hardware may go into bad state.
Listen to USB cable notifications with high priority. If
simulation is running and cable is removed, tear down the
DP session before USB re-programs the PHY.

CRs-Fixed: 2338665
Change-Id: I55955583dd44cb42c778c2ab32a190ddd9a7e72e
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>