class_docstr: The implementation of ConvFFN unsed in Extractor.
code: def forward(self, x, H, W):
      x = self.fc1(x)
      x = self.dwconv(x, H, W)
      x = self.act(x)
      x = self.drop(x)
      x = self.fc2(x)
      x = self.drop(x)
      return x
  
imports: import math
  import warnings
  from functools import partial
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg.models.backbones.transformer_utils import DropPath
  from paddleseg.models.layers.ms_deformable_attention import MSDeformAttn
label_desc: Use image node_id 2 for calling the ConvFFN obj's underlying member method code with example usage: obj.forward(x, H, W) and returns: x