qeth: remove locks from sysfs _show

Locking is probably unnecessary in this case, and the rest of the
qeth sysfs code does not use locks in the *_show() functions.
Remove locks from the layer2 *_show() functions in which they where
accidentally introduced.

Signed-off-by: Eugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>