hwc/overlay: Fix decimation / bwc bugs

1) While setting BWC check for 90 transform and swap crop
2) Calculate decimation in the getDecimationFactor API itself.
   Currently, a residual downscale is calculated and the clients have
   to take logs and apply forcible decimation like in MdpCtrl
3) Fix bug where transform gets typecasted to bool

b/14225977

Change-Id: I3c99c571e02e2cf7822342516b6a87d97be553d1
diff --git a/liboverlay/overlayUtils.h b/liboverlay/overlayUtils.h
index c2649f3..39507f2 100644
--- a/liboverlay/overlayUtils.h
+++ b/liboverlay/overlayUtils.h
@@ -413,8 +413,8 @@
 int getDownscaleFactor(const int& src_w, const int& src_h,
         const int& dst_w, const int& dst_h);
 void getDecimationFactor(const int& src_w, const int& src_h,
-        const int& dst_w, const int& dst_h, float& horDscale,
-        float& verDscale);
+        const int& dst_w, const int& dst_h, uint8_t& horzDeci,
+        uint8_t& vertDeci);
 
 /* flip is upside down and such. V, H flip
  * rotation is 90, 180 etc