[Transformer2DModel] don't norm twice (#1381)

don't norm twice

src/diffusers/models/attention.py

@@ -201,13 +201,11 @@ class Transformer2DModel(ModelMixin, ConfigMixin):
             residual = hidden_states
 
             hidden_states = self.norm(hidden_states)
-
             if not self.use_linear_projection:
                 hidden_states = self.proj_in(hidden_states)
                 inner_dim = hidden_states.shape[1]
                 hidden_states = hidden_states.permute(0, 2, 3, 1).reshape(batch, height * weight, inner_dim)
             else:
-                hidden_states = self.norm(hidden_states)
                 inner_dim = hidden_states.shape[1]
                 hidden_states = hidden_states.permute(0, 2, 3, 1).reshape(batch, height * weight, inner_dim)
                 hidden_states = self.proj_in(hidden_states)