xpu support inplace flatten (#48909)

This is a PR to catch up with latest xpu white list strategy
(https://github.com/PaddlePaddle/Paddle/pull/48606)
, since original list only include 'fluid' fashion names, but new list
must include 'phi' fashion as well.
Refer to paddle/phi/core/kernel_factory.cc for more details.

paddle/phi/backends/xpu/xpu2_op_list.cc

@@ -227,6 +227,12 @@ XPUOpMap& get_kl2_ops() {
                      phi::DataType::INT8,
                      phi::DataType::FLOAT16,
                      phi::DataType::FLOAT32})},
+      {"flatten_with_xshape",
+       XPUKernelSet({phi::DataType::INT64,
+                     phi::DataType::INT32,
+                     phi::DataType::INT8,
+                     phi::DataType::FLOAT16,
+                     phi::DataType::FLOAT32})},
       {"flatten_grad",
        XPUKernelSet({phi::DataType::INT64,
                      phi::DataType::INT32,