mdss: display-port: add support to send HPD event to framework

Add support to send switch event to framework when the HDP
status changes. This switch event is shared between HDMI and
DP.

Change-Id: I13161bd8b2a7777abbe2521178c5b1b1b6416eea
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>