msm: mdss: hdmi: add pin-control and splash enable

Initialize the splash enabled flag when HDMI is primary.
This is required during probe time so the HDMI driver can
add pin-control vote, enable regulators, enable GPIOs and
enable clocks.

Change-Id: Iaaf3d983512619bda753b12e3d80ee8efe32d810
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>