fixed a typo that mis-used Y plane stride for UV blocks.

Raised by Lei Yang, the Y plane stride was used for UV blocks.
This is clearly a typo. But as the comments in the code suggested
that this port of code has not been used yet, so the typo should
not have created any damage yet.

Change-Id: Iea895edc17469a51c803a8cc6d0fce65a1a7fc2f

vp8/common/reconinter.c

@@ -669,11 +669,15 @@ void vp8_build_inter_predictors_mb_s(MACROBLOCKD *x)
 
                 if (d0->bmi.mv.as_mv.row & 7 || d0->bmi.mv.as_mv.col & 7)
                 {
-                    x->subpixel_predict8x4(ptr, d0->pre_stride, d0->bmi.mv.as_mv.col & 7, d0->bmi.mv.as_mv.row & 7, dst_ptr, x->dst.y_stride);
+                    x->subpixel_predict8x4(ptr, d0->pre_stride,
+                        d0->bmi.mv.as_mv.col & 7,
+                        d0->bmi.mv.as_mv.row & 7,
+                        dst_ptr, x->dst.uv_stride);
                 }
                 else
                 {
-                    RECON_INVOKE(&x->rtcd->recon, copy8x4)(ptr, d0->pre_stride, dst_ptr, x->dst.y_stride);
+                    RECON_INVOKE(&x->rtcd->recon, copy8x4)(ptr,
+                        d0->pre_stride, dst_ptr, x->dst.uv_stride);
                 }
             }
             else