drm/msm/dsi-staging: add DSI 7nm PHY and DSI ctrl 2.3 support

This change adds DSI timing calculator and PHY configuration
support for 7nm DSI PHY version. This change also adds support
for DSI controller version 2.3.

Change-Id: Ia430fd1e3d6e585940ba10d1538425753663f4e8
Signed-off-by: Govinda Rajulu Chenna <gchenna@codeaurora.org>