hwc: fix dst calculations for right mixer

The calculations made for the right mixer was not correct,
fixed it for both FBUpdate and video usecases

Change-Id: Iff2c296321bce14b776731528fff6f1d255d829a
diff --git a/libhwcomposer/hwc_utils.cpp b/libhwcomposer/hwc_utils.cpp
index 013833f..f9b1afc 100644
--- a/libhwcomposer/hwc_utils.cpp
+++ b/libhwcomposer/hwc_utils.cpp
@@ -798,6 +798,8 @@
     if(rDest != OV_INVALID) {
         PipeArgs pargR(mdpFlagsR, whf, z, isFg,
                 static_cast<eRotFlags>(rotFlags));
+        tmp_dstR.right = tmp_dstR.right - tmp_dstR.left;
+        tmp_dstR.left = 0;
         if(configMdp(ctx->mOverlay, pargR, orient,
                 tmp_cropR, tmp_dstR, rDest) < 0) {
             ALOGE("%s: commit failed for right mixer config", __FUNCTION__);