virtio: fix cli parsing for tx-queue-size

The previous change made CSIT virtio tests fail,
but those tests are not part of trending.

Ticket: VPP-2088
Type: fix
Fixes: a181eaa59bb2ff2784376918e95bbf92e5340db1

Change-Id: If0439a030c051894e07007da9cf0a2e4dc1434c3
Signed-off-by: Vratko Polak <vrpolak@cisco.com>
diff --git a/src/vnet/devices/virtio/cli.c b/src/vnet/devices/virtio/cli.c
index cadfd67..45642d6 100644
--- a/src/vnet/devices/virtio/cli.c
+++ b/src/vnet/devices/virtio/cli.c
@@ -44,7 +44,7 @@
 	;
       else if (unformat (line_input, "feature-mask 0x%llx", &feature_mask))
 	args.features = feature_mask;
-      if (unformat (line_input, "tx-queue-size %u", &txq_size))
+      else if (unformat (line_input, "tx-queue-size %u", &txq_size))
 	args.tx_queue_size = txq_size;
       else if (unformat (line_input, "gso-enabled"))
 	args.gso_enabled = 1;