configfs: change depends -> select SYSFS

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: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Acked-by: Joel Becker <jlbec@evilplan.org>

fs/configfs/Kconfig

 config CONFIGFS_FS
 	tristate "Userspace-driven configuration filesystem"
-	depends on SYSFS
+	select SYSFS
 	help
-	  configfs is a ram-based filesystem that provides the converse
+	  configfs is a RAM-based filesystem that provides the converse
 	  of sysfs's functionality. Where sysfs is a filesystem-based
 	  view of kernel objects, configfs is a filesystem-based manager
 	  of kernel objects, or config_items.