drm/msm/dp: perform mst phy operations during suspend resume

Perform mst phy operations during suspend/resume
to allow sinks to be in a correct state. A usbpd
api must also be called before and after the phy
operations to allow the system to go into deep
suspend and resume in a timely manner.

CRs-Fixed: 2363921
Change-Id: I67facef3f453d67f63814f96647e51e0b0fafd45
Signed-off-by: Fuad Hossain <fhossain@codeaurora.org>