A misplaced #endif in ixgbe_ioctl() causes interface MTU to become
zero when INET and INET6 are undefined.

PR: 162028
Differential Revision: https://reviews.freebsd.org/D3187
Submitted by: hoomanfazaeli@gmail.com pluknet
Reviewed by: erj hiren gelbius
MFC after: 2 weeks