[Versatile] fix attention mask (#1763)

src/diffusers/models/attention.py

@@ -959,6 +959,7 @@ class DualTransformer2DModel(nn.Module):
 
         encoded_states = []
         tokens_start = 0
+        # attention_mask is not used yet
         for i in range(2):
             # for each of the two transformers, pass the corresponding condition tokens
             condition_state = encoder_hidden_states[:, tokens_start : tokens_start + self.condition_lengths[i]]
@@ -967,7 +968,6 @@ class DualTransformer2DModel(nn.Module):
                 input_states,
                 encoder_hidden_states=condition_state,
                 timestep=timestep,
-                attention_mask=attention_mask,
                 return_dict=False,
             )[0]
             encoded_states.append(encoded_state - input_states)