Make the ixgbe tunables now match their sysctl counterparts.

Make the ixgbe tunables now match their sysctl counterparts.

Previously the tunables and sysctls had different names for example:
hw.ixgbe.enable_aim => hw.ix.enable_aim

Anyone using ixgbe tunables should ensure they update /boot/loader.conf.

This is a direct commit to stable as the changes to sysctls in head
already fix this issue in a different way.

Sponsored by:	Multiplay

git-svn-id: svn://svn.freebsd.org/base/stable/10@269975 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f