[Bugfix][Quantization] Reject unsupported compressed tensors KV cache schemes (#45312)

Signed-off-by: Ting Sun <suntcrick@gmail.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

vllm/model_executor/layers/quantization/compressed_tensors/compressed_tensors.py

@@ -983,7 +983,7 @@ class CompressedTensorsKVCacheMethod(BaseKVCacheMethod):
         type_ = kv_cache_scheme.get("type")
         num_bits = kv_cache_scheme.get("num_bits")
 
-        if type_ != "float" and num_bits != 8:
+        if type_ != "float" or num_bits != 8:
             raise NotImplementedError(
                 "Currently supported kv cache quantization is "
                 "num_bits=8, type=float, however "