removing unnecessary else statement (huggingface#11624)

Co-authored-by: Aryan <aryan@huggingface.co>

Author: YanivDorGalron

src/diffusers/models/transformers/transformer_flux.py

@@ -447,8 +447,6 @@ def forward(
         timestep = timestep.to(hidden_states.dtype) * 1000
         if guidance is not None:
             guidance = guidance.to(hidden_states.dtype) * 1000
-        else:
-            guidance = None
 
         temb = (
             self.time_text_embed(timestep, pooled_projections)