bus/vdev: fix finding device by name

bus/vdev: fix finding device by name

Use strcmp to compare device names as the strncmp in original code
causes find_vdev to return -EEXIST  for names that are prefix
of another. The creation of interfaces fails unpredictably based
on the order of their creation. An easy way hit this bug is to create
eth_vhost1 after eth_vhost11.

Fixes: dda987315ca2 ("vdev: make virtual bus use its device struct")
Cc: stable@dpdk.org
Signed-off-by: Nachiketa Prachanda <nprachan@vyatta.att-mail.com>
Acked-by: Jianfeng Tan <jianfeng.tan@intel.com>