Revert "Merge pull request #141 from jet47/gpu-pyrlk-fix" because this bug appears only in 2.4

This reverts commit 7e301c5c, reversing
changes made to b5e009eb.

modules/gpu/src/pyrlk.cpp

@@ -211,9 +211,6 @@ void cv::gpu::PyrLKOpticalFlow::dense(const GpuMat& prevImg, const GpuMat& nextI
         pyrDown(nextPyr_[level - 1], nextPyr_[level]);
     }
 
-    uPyr_.resize(2);
-    vPyr_.resize(2);
-
     ensureSizeIsEnough(prevImg.size(), CV_32FC1, uPyr_[0]);
     ensureSizeIsEnough(prevImg.size(), CV_32FC1, vPyr_[0]);
     ensureSizeIsEnough(prevImg.size(), CV_32FC1, uPyr_[1]);