examples/ethtool: fix two typos

examples/ethtool: fix two typos

This patch fixes 2 typos in examples/ethtool:

There is no such thing as ethtool_ops::get_driverinfo
It should be get_drvinfo:
see include/linux/ethtool.h in the kernel tree.

rte_net_change_mtu should be ndo_change_mtu:
see include/linux/netdevice.h in the kernel tree.

Fixes: bda68ab9d1e7 ("examples/ethtool: add user-space ethtool sample application")
Cc: stable@dpdk.org
Signed-off-by: Rami Rosen <ramirose@gmail.com>
Acked-by: Remy Horton <remy.horton@intel.com>