examples/ethtool: disable promiscuous mode by default
examples/ethtool: disable promiscuous mode by default

Disable promiscuous mode by default since VLAN filter
does not work when promiscuous mode is enabled.

Signed-off-by: Qi Zhang <9e9e58ffa71a29bb7b87766b362515be648fcbe0@intel.com>
Acked-by: Remy Horton <34c343e92f0e27f7a8e26a1d8d2146ae7c7dd1a3@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk