make dropout oprional #2

utils/generic_utils.py

@@ -262,6 +262,7 @@ def setup_model(num_chars, c):
             attn_win=c.windowing,
             attn_norm=c.attention_norm,
             prenet_type=c.prenet_type,
+            prenet_dropout=c.prenet_dropout,
             forward_attn=c.use_forward_attn,
             trans_agent=c.transition_agent,
             location_attn=c.location_attn)