drm: msm: add early splash support on triple displays

This patch is to support early splash on triple displays
including DSI-HDMI displays and native HDMI display, for
auto products.

CRs-Fixed: 2225630
Change-Id: I4de17eabbf2b2caf1354390f327ba7b761dc313f
Signed-off-by: Guchun Chen <guchunc@codeaurora.org>
Signed-off-by: Camus Wong <camusw@codeaurora.org>