[TPU] Update pallas.py to support trillium (#8871)

Author: bvrockwell

vllm/attention/backends/pallas.py

@@ -130,7 +130,7 @@ def __init__(
         assert tpu_type is not None
         tpu_type = tpu_type.lower()
 
-        if "lite" not in tpu_type:
+        if (("lite" not in tpu_type) and ("v6" not in tpu_type)):
             if self.num_kv_heads % 2 == 0:
                 self.megacore_mode = "kv_head"
             else: