fix HPU could not handle float16 in attention.py.

attention.py

@@ -46,9 +46,8 @@ def scaled_multihead_dot_product_attention(query, key, value, n_heads, past_key_
         attn_weight = attn_weight.masked_fill(~key_padding_mask.view((b, 1, 1, s_k)), min_val)
     if is_causal and (not q.size(2) == 1):
         s = max(s_q, s_k)
-        causal_mask = attn_weight.new_ones(s, s, dtype=torch.float16)
+        causal_mask = attn_weight.new_ones(s, s, dtype=torch.bool)
         causal_mask = causal_mask.tril()
-        causal_mask = causal_mask.to(torch.bool)
         causal_mask = ~causal_mask
         causal_mask = causal_mask[-s_q:, -s_k:]
         attn_weight = attn_weight.masked_fill(causal_mask.view(1, 1, s_q, s_k), min_val)
@@ -297,4 +296,4 @@ def build_alibi_bias(n_heads, seq_len, full=False, alibi_bias_max=8, device=None
     slopes = gen_slopes(n_heads, alibi_bias_max, device=device)
     alibi_bias = alibi_bias * slopes
     return alibi_bias.to(dtype=dtype)
-ATTN_CLASS_REGISTRY = {'multihead_attention': MultiheadAttention, 'multiquery_attention': MultiQueryAttention}
+ATTN_CLASS_REGISTRY = {'multihead_attention': MultiheadAttention, 'multiquery_attention': MultiQueryAttention}