[dts] [PATCH V1] tests/TestSuite_vhost_1024_ethports: adapt max vdev number to 1023

[Tu, Lijuan]

> The value of MAX_FDS is 1024 and there is an extra global fd, DPDK limits the
> number of vdev to 1023, so modify script to adapt.
> 
> Signed-off-by: JiangYu <yux.jiang at intel.com>

Applied