fs: omfs: Initialize filesystem timestamp ranges

Fill in the appropriate limits to avoid inconsistencies
in the vfs cached inode times when timestamps are
outside the permitted range.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Bob Copeland <me@bobcopeland.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Cc: me@bobcopeland.com
Cc: linux-karma-devel@lists.sourceforge.net