cxgb4vf: remove obsolete DECLARE_PCI_UNMAP_ADDR usage

We could use DEFINE_DMA_UNMAP_ADDR instead but using
CONFIG_NEED_DMA_MAP_STATE is a simpler way to see if a platform does
real DMA unmapping.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/cxgb4vf/sge.c b/drivers/net/cxgb4vf/sge.c
index 3a7c02f..4bc1858 100644
--- a/drivers/net/cxgb4vf/sge.c
+++ b/drivers/net/cxgb4vf/sge.c
@@ -228,15 +228,11 @@
  */
 static inline int need_skb_unmap(void)
 {
-	/*
-	 * This structure is used to tell if the platfrom needs buffer
-	 * unmapping by checking if DECLARE_PCI_UNMAP_ADDR defines anything.
-	 */
-	struct dummy {
-		DECLARE_PCI_UNMAP_ADDR(addr);
-	};
-
-	return sizeof(struct dummy) != 0;
+#ifdef CONFIG_NEED_DMA_MAP_STATE
+	return 1;
+#else
+	return 0;
+#endif
 }
 
 /**