msm: mdss: displayport: fix alt mode sequence

Some sinks expect configure command before notifying hpd
as high in status or attention command. Do not wait for
hpd to go high to send configure command to sink. Once the
configure command has been sent to sink, sink may send attention
command back to source with hpd high. Configure source power on
if attention command is received with hpd high.

Change-Id: Ic5254da65f3720a8313881bc419ec912a0ed6997
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>