[UT][intel GPU] use current_platform instead of device hardcode in v1 tests (#20169)

Signed-off-by: Ma, Liangliang <liangliang.ma@intel.com>

vllm/v1/attention/backends/mla/common.py

@@ -217,7 +217,8 @@ try:
     is_vllm_fa = True
 except ImportError:
     # For rocm use upstream flash attention
-    from flash_attn import flash_attn_varlen_func
+    if current_platform.is_rocm():
+        from flash_attn import flash_attn_varlen_func
     is_vllm_fa = False
 
 if TYPE_CHECKING: