delete useless .h header in DepthwiseConvOpGpu.cu

paddle/function/DepthwiseConvOpGpu.cu

@@ -12,7 +12,6 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License. */
 
-#include <algorithm>
 #include "DepthwiseConvOp.h"
 #include "GemmFunctor.h"
 #include "paddle/math/BaseMatrix.h"