qeth: sysfs: replace strcmp() with sysfs_streq()

Replace combination of strsep() and a temporary char *
followed by a series of "if (!strcmp(...))" with a series
of "if (sysfs_streq(...))".

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