Stop requiring CAP_NET_ADMIN

Stop requiring CAP_NET_ADMIN

Since the following commit in the Linux kernel tree

  0fdc100bdc4b ethtool: allow non-netadmin to query settings

it is no longer necessary to have the CAP_NET_ADMIN capability to query
a device speed using ioctl(..., SIOCETHTOOL) in conjonction with the
ETHTOOL_GSET ethtool command.

The mentioned commit landed first in the 2.6.37 version of the Kernel.
This version is no longer maintained nowdays.

Since it is not necessary anymore, it is strongly prefered from a
security standpoint to drop the CAP_NET_ADMIN capability from the
binary.

Signed-off-by: Olivier Gayot <olivier.gayot@sigexec.com>