[BugFix] Fix false assertion with spec-decode=[2,4,..] and TP>2 (#29036)

Signed-off-by: Lucas Wilkinson <lwilkins@redhat.com>

Author: LucasWilkinson

vllm/config/compilation.py

@@ -921,7 +921,7 @@ def adjust_cudagraph_sizes_for_spec_decode(
         self, uniform_decode_query_len: int, tensor_parallel_size: int
     ):
         multiple_of = uniform_decode_query_len
-        if tensor_parallel_size > 1:
+        if tensor_parallel_size > 1 and self.pass_config.enable_sequence_parallelism:
             multiple_of = max(uniform_decode_query_len, tensor_parallel_size)
             if (
                 multiple_of % uniform_decode_query_len != 0