i40e: use correct length for strncpy

i40e: use correct length for strncpy

BugLink: https://bugs.launchpad.net/bugs/1853915
[ Upstream commit 7eb74ff891b4e94b8bac48f648a21e4b94ddee64 ]

Caught by GCC 8. When we provide a length for strncpy, we should not
include the terminating null. So we must tell it one less than the size
of the destination buffer.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>