staging: et131x: Add ethtool printout to match MII regs

In the ethtool call et131x_get_regs(), some MII regs are missing.
Add them to the regs returned.

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>