examples/vhost_crypto: remove unused function

This patch tries to fix the coverity issue of unchecked
return value. Since the function that causes the problem
is unused, it is removed completely.

Coverity issue: 336816
Fixes: f518821 ("examples/vhost_crypto: add sample application")
Cc: stable@dpdk.org

Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
Acked-by: Marko Kovacevic <marko.kovacevic@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

examples/vhost_crypto/main.c

@@ -354,12 +354,6 @@ static const struct vhost_device_ops virtio_crypto_device_ops = {
 	.destroy_device = destroy_device,
 };
 
-__attribute__((unused))
-static void clrscr(void)
-{
-	system("@cls||clear");
-}
-
 static int
 vhost_crypto_worker(void *arg)
 {