eal: fix device iterator when no bus is selected

Devargs used in device iterator initialization wasn't set to zero, random
data like bus string lead to invalid address access.

This patch initializes devargs.

Bugzilla ID: 862
Fixes: c99a2d4 ("eal: implement device iteration initialization")
Cc: stable@dpdk.org

Signed-off-by: Xueming Li <xuemingl@nvidia.com>

lib/eal/common/eal_common_dev.c

@@ -573,7 +573,7 @@ int
 rte_dev_iterator_init(struct rte_dev_iterator *it,
 		      const char *dev_str)
 {
-	struct rte_devargs devargs;
+	struct rte_devargs devargs = { .bus = NULL };
 	struct rte_class *cls = NULL;
 	struct rte_bus *bus = NULL;