RDMA/mlx4: Initialize ib_spec on the stack

Initialize ib_spec on the stack before using it, otherwise we will have
garbage values that will break creating default rules with invalid parsing
error.

Fixes: a37a1a4 ("IB/mlx4: Add mechanism to support flow steering over IB links")
Link: https://lore.kernel.org/r/20200413132235.930642-1-leon@kernel.org
Signed-off-by: Alaa Hleihel <alaa@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx4/main.c

@@ -1499,8 +1499,9 @@ static int __mlx4_ib_create_default_rules(
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(pdefault_rules->rules_create_list); i++) {
+		union ib_flow_spec ib_spec = {};
 		int ret;
-		union ib_flow_spec ib_spec;
+
 		switch (pdefault_rules->rules_create_list[i]) {
 		case 0:
 			/* no rule */