intel: i40e: fix confused code

This code is pretty confused. The variable name 'bytes_not_copied'
clearly indicates that the programmer knew the semantics of
copy_{to,from}_user, but then the return value is checked for being
negative and used as a -Exxx return value.

I'm not sure this is the proper fix, but at least we get rid of the
dead code which pretended to check for access faults.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>