hwc: Partial update support for dual DSI panels with source
split.

1) When source split is enabled, both the panels are calibrated
   in a single coordinate system. So only one ROI is generated
   for the whole panel extending equally from the midpoint and
   populated for the left side.
2) Fixes a bug in mdpcomp where ROI generated for the frame is
   reset when a strategy fails.

Change-Id: I47fa0e827985dd76d06dcbe464ef832cfc57a671
diff --git a/libhwcomposer/hwc.cpp b/libhwcomposer/hwc.cpp
index adf48e7..bf59217 100644
--- a/libhwcomposer/hwc.cpp
+++ b/libhwcomposer/hwc.cpp
@@ -635,7 +635,11 @@
             }
         }
 
-        int lSplit = getLeftSplit(ctx, dpy);
+        /* When source split is enabled, right ROI will always be NULL since the
+         * ROI for the whole panel generated in a single coordinate system will
+         * be populuated in left ROI. So leave the right ROI untouched */
+        int lSplit = qdutils::MDPVersion::getInstance().isSrcSplit() ? 0
+                :getLeftSplit(ctx, dpy);
         qhwc::ovutils::Dim lRoi = qhwc::ovutils::Dim(
             ctx->listStats[dpy].lRoi.left,
             ctx->listStats[dpy].lRoi.top,