configfs: Replace CURRENT_TIME by current_fs_time()

CURRENT_TIME macro is not appropriate for filesystems as it
doesn't use the right granularity for filesystem timestamps.
Use current_fs_time() instead.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>