ethtool.sh didn't reset the Internal Field Seperator (IFS) properly.
It now does, by storing the old IFS to OIFS, which will be used later
in the for loop.
It also fixes the "ethtool_ring_<if>" option.
Reported-by: Alois Schmid <alois.schmid@gmx.de>
X-Gentoo-Bug: 368525
X-Gentoo-Bug-URL: https://bugs.gentoo.org/368525