Fix the AMD weight loading tests (vllm-project#8390)

Author: mgoin

vllm/config.py

@@ -883,7 +883,7 @@ def __init__(
             from vllm.executor import ray_utils
             backend = "mp"
             ray_found = ray_utils.ray_is_available()
-            if (torch.cuda.is_available()
+            if (current_platform.is_cuda()
                     and cuda_device_count_stateless() < self.world_size):
                 if not ray_found:
                     raise ValueError("Unable to load Ray which is "