drm/msm/dsi-staging: add support for configuring display topology

Display topology is influenced by the target capabilities
and the panel features. This change allows the sde display
device tree to list down the possible topologies valid on
the target and default topology selected for the display.
The change also provides options to override the default
topology through kernel boot parameters.

Change-Id: Ie7b3c6ba5d79965c3247a629e992df9baded6ecd
Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>