fix the but that concat op can't support uint8 (#33667)

Author: youth123

paddle/fluid/operators/concat_op.cc

@@ -244,4 +244,4 @@ REGISTER_OP_CPU_KERNEL(
     ops::ConcatGradKernel<paddle::platform::CPUDeviceContext,
                           paddle::platform::float16>,
     ops::ConcatGradKernel<paddle::platform::CPUDeviceContext, int>,
-    ops::ConcatKernel<paddle::platform::CPUDeviceContext, uint8_t>);
+    ops::ConcatGradKernel<paddle::platform::CPUDeviceContext, uint8_t>);

paddle/fluid/operators/concat_op.cu.cc

@@ -33,4 +33,4 @@ REGISTER_OP_CUDA_KERNEL(
     ops::ConcatGradKernel<paddle::platform::CUDADeviceContext, plat::float16>,
     ops::ConcatGradKernel<paddle::platform::CUDADeviceContext, int64_t>,
     ops::ConcatGradKernel<paddle::platform::CUDADeviceContext, int>,
-    ops::ConcatKernel<paddle::platform::CUDADeviceContext, uint8_t>);
+    ops::ConcatGradKernel<paddle::platform::CUDADeviceContext, uint8_t>);