There is no technical limitation in device mapper that would prevent the
dm-stripe target from using a stripe size smaller than page size.

This patch removes the limit and makes stripe volumes portable across
architectures with different page size.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>