net/dpaa2: fix build with GCC 15

Compiler no longer allows initializing byte array with string.
warning: initializer-string for array of ‘unsigned char’ is too long
	 [-Wunterminated-string-initialization]
  169 |         .vni = "\xff\xff\xff",
      |                ^~~~~~~~~~~~~~

Fixes: 39c8044 ("net/dpaa2: support VXLAN flow matching")

Signed-off-by: Stephen Hemminger <[email protected]>
Acked-by: Ferruh Yigit <[email protected]>

drivers/net/dpaa2/dpaa2_flow.c

@@ -166,7 +166,7 @@ static const struct rte_flow_item_gre dpaa2_flow_item_gre_mask = {
 
 static const struct rte_flow_item_vxlan dpaa2_flow_item_vxlan_mask = {
 	.flags = 0xff,
-	.vni = "\xff\xff\xff",
+	.vni = { 0xff, 0xff, 0xff },
 };
 
 static const struct rte_flow_item_ecpri dpaa2_flow_item_ecpri_mask = {