This patch changes configfs to select SYSFS to fix the following:

warning: (TARGET_CORE && GFS2_FS) selects CONFIGFS_FS which has unmet direct dependencies (SYSFS)
Reported-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NNicholas A. Bellinger <nab@linux-iscsi.org>
Acked-by: NJoel Becker <jlbec@evilplan.org>