This is part 3 of the support for the new Intel Ethernet E610
family of devices

The ix driver now enables firmware logging on Intel E610 devices
for debugging with Customer Support. Logs are enabled by default
and generated in binary format that requires decoding by support
teams. The collected data is firmware and hardware related for
debugging purposes only.

When the driver loads, it creates a fw_log sysctl node under the
debug section. Events are organized into categories (modules) for
targeted logging, and users can adjust verbosity levels as needed.

This adds sysctl support for the firmware logging feature and
updates the ix(4) manual page with documentation.

Signed-off-by: Yogesh Bhosale <yogesh.bhosale@intel.com>
Co-developed-by: Krzysztof Galazka <krzysztof.galazka@intel.com>