staging: fieldbus core: remove unused strings

Remove two unused static const strings - a leftover from
a previous stage. Interestingly, neither gcc nor sparse
warned about their presence.
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Link: https://lore.kernel.org/r/20190918183552.28959-2-TheSven73@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fieldbus/dev_core.c

@@ -23,9 +23,6 @@ static dev_t fieldbus_devt;
 static DEFINE_IDA(fieldbus_ida);
 static DEFINE_MUTEX(fieldbus_mtx);
 
-static const char ctrl_enabled[] = "enabled";
-static const char ctrl_disabled[] = "disabled";
-
 static ssize_t online_show(struct device *dev, struct device_attribute *attr,
 			   char *buf)
 {