drm/msm/mdp5: Add hardware configuration for msm8x16

This change adds the hw configuration for msm8x16 chipsets in
mdp5_cfg module.

Note that only one external display interface is present in this
configuration (DSI) but has not been enabled yet. It will be enabled
once drm/msm driver supports DSI connectors.

v2: add CTL flush register's hardware mask [pointed by Archit]

Signed-off-by: Stephane Viau <sviau@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>