revert "s390/net: lcs: use IS_ENABLED() for kconfig detection"

The referenced patch is causing build errors when ETHERNET=y and
FDDI=m. While we work out the preferred patch(es), revert this patch
to make the pain go away.

Fixes: 12827233 ("s390/net: lcs: use IS_ENABLED() for kconfig detection")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Link: lore.kernel.org/r/202306202129.pl0AqK8G-lkp@intel.com
Cc: Alexandra Winter <wintera@linux.ibm.com>
Cc: Wenjia Zhang <wenjia@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230622155409.27311-1-rdunlap@infradead.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>