Update paddings computed to adjust selected_token_indices (HabanaAI#210)

Fixes assert seen when "prompt_logprobs is not None" and BS > 1. Assert
was due to shape of paddings being added to matching
sampling_metadata.selected_token_indices shape for the case where
prompt_logprobs is configured.

vllm/worker/habana_model_runner.py

@@ -1012,8 +1012,13 @@ def prepare_input_tensors(
         paddings = [max_len - s for s in seq_lens]
         paddings = [0] + paddings[:-1]
         paddings = list(itertools.accumulate(paddings))
+        paddings_prompt_logprobs = []
+        for i, seq_group_metadata in enumerate(seq_group_metadata_list):
+            if seq_group_metadata.sampling_params.prompt_logprobs is not None \
+                              and seq_group_metadata.is_prompt:
+                paddings_prompt_logprobs += ([paddings[i]] * seq_lens[i])
         paddings = torch.tensor(
-            paddings,
+            paddings_prompt_logprobs if paddings_prompt_logprobs else paddings,
             dtype=sampling_metadata.selected_token_indices.dtype,
             device=sampling_metadata.selected_token_indices.device)
         sampling_metadata.selected_token_indices.add_(paddings)