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

According to the disscussion in
https://patchwork.kernel.org/patch/8308691/ we agreed to use
unsigned 32 bit timestamps on ceph.
Update the limits accordingly.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Cc: zyan@redhat.com
Cc: sage@redhat.com
Cc: idryomov@gmail.com
Cc: ceph-devel@vger.kernel.org