hwc: Add target specific checks in hwcomposer

* Mdss driver supports DMA-Multiplexing on wb interface
for certain targets. Add overlay get function to query
this info during pipe allocation for wb.

* UI Scaling on external is not supported on certain
targets due to the lack of availability of pipes with
scalars. Add overlay get function to query this info
to disable action-safe calcs, DRC and others which
require downscaling.

Change-Id: I1726caa4634f72d781561e797078648524ea2eef
diff --git a/libhwcomposer/hwc_mdpcomp.cpp b/libhwcomposer/hwc_mdpcomp.cpp
index 40fa624..d008147 100644
--- a/libhwcomposer/hwc_mdpcomp.cpp
+++ b/libhwcomposer/hwc_mdpcomp.cpp
@@ -403,7 +403,8 @@
     if(!isEnabled()) {
         ALOGD_IF(isDebug(),"%s: MDP Comp. not enabled.", __FUNCTION__);
         ret = false;
-    } else if(qdutils::MDPVersion::getInstance().is8x26() &&
+    } else if((qdutils::MDPVersion::getInstance().is8x26() ||
+               qdutils::MDPVersion::getInstance().is8x16()) &&
             ctx->mVideoTransFlag &&
             isSecondaryConnected(ctx)) {
         //1 Padding round to shift pipes across mixers