Revert merging of pull request #5176 from vladimir-dudnik:master (reverted from…

Revert merging of pull request #5176 from vladimir-dudnik:master (reverted from commit 5ee00ec5)

modules/core/src/ocl.cpp

@@ -4572,8 +4572,6 @@ public:
                     else
                     {
                         // CL_MEM_USE_HOST_PTR (nothing is required) and OTHER cases
-                        if (u->flags & UMatData::USER_ALLOCATED)
-                        {
                         cl_int retval = 0;
                         void* data = clEnqueueMapBuffer(q, (cl_mem)u->handle, CL_TRUE,
                                                         (CL_MAP_READ | CL_MAP_WRITE),
@@ -4583,7 +4581,6 @@ public:
                         CV_OclDbgAssert(clFinish(q) == CL_SUCCESS);
                     }
                 }
-                }
                 u->markHostCopyObsolete(false);
             }
 #ifdef HAVE_OPENCL_SVM