fix include for multiplex_grad_kernel (PaddlePaddle#2204)

Author: fsylmxx

backends/iluvatar_gpu/kernels/cuda_kernels/multiplex_grad_kernel_register.cu

@@ -13,7 +13,7 @@
 // limitations under the License.
 // clang-format off
 #include "paddle/phi/core/kernel_registry.h"
-#include "paddle/phi/kernels/gpu/multiplex_grad_kernel.cu" // NOLINT
+#include "paddle/phi/kernels/multiplex_grad_kernel.h" // NOLINT
 #include "paddle/phi/kernels/multinomial_kernel.h"
 // clang-format on
 PD_CUSTOM_KERNEL_REGISTER(multiplex_grad,

backends/metax_gpu/kernels/cuda_kernels/multiplex_grad_kernel_register.cu

@@ -14,7 +14,7 @@
 // limitations under the License.
 // clang-format off
 #include "paddle/phi/core/kernel_registry.h"
-#include "paddle/phi/kernels/gpu/multiplex_grad_kernel.cu" // NOLINT
+#include "paddle/phi/kernels/multiplex_grad_kernel.h" // NOLINT
 #include "paddle/phi/kernels/multinomial_kernel.h"
 // clang-format on
 PD_CUSTOM_KERNEL_REGISTER(multiplex_grad,