ehea: fix sysfs link compile problem

Due to changes in the struct device_driver there is no direct
access to its kobj any longer. The kobj was used to create
sysfs links between eHEA ethernet devices and the driver.
This patch removes the affected sysfs links to resolve
the build problems.

Signed-off-by: Jan-Bernd Themann <themann@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>