drm/msm/dp: fix link training during system resume

Power on the link clocks and complete the link training
when coming out of deep sleep. This is required as all
the DisplayPort clocks are shutdown during suspend. On
wake-up, enable the required clocks and complete the
link training as DisplayPort status may have changed
during sleep.

CRs-Fixed: 2294347
Change-Id: Ibeaf21448507415343aac307b4fab8f6e3609b74
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>