host QoS: have service curve parameters be integers

It does not make sense to represent fraction of bits, specially when
we get the information from the kernel (though indirectly) and the
kernel external representation is in integer bps.

Change-Id: Id91438cf35d945be9d7e2f51b48b36071838829e
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/34822
Tested-by: Lior Vernia <lvernia@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>