configfs: init configfs module earlier at boot time

We need this earlier in the boot process to allow various subsystems to
use configfs (e.g Industrial IIO).

Also, debugfs is at core_initcall level and configfs should be on the same
level from infrastructure point of view.

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Suggested-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>