RDMA/cxgb3: Propagate HW page size capabilities

cxgb3 does not currently report the page size capabilities, and
incorrectly reports them internally.

This version changes the bit-shifting to a static value (per Steve's
request).

Signed-off-by: Jon Mason <jon@opengridcomputing.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>