enetc: Fix endianness issues for enetc_ethtool

commit e38dc6a6b129cb3d21539b406a2bfb8545fb4b90 from
git://source.codeaurora.org/external/qoriq/qoriq-components/linux



These particular fields are specified in the H/W reference
manual as having network byte order format, so enforce big
endian annotation for them and clear the related sparse
warnings in the process.

Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit d548d393)
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Meng Li <Meng.Li@windriver.com>