IB: simplify static rate encoding

Push translation of static rate to HCA format into low-level drivers,
where it belongs.  For static rate encoding, use encoding of rate
field from IB standard PathRecord, with addition of value 0, for
backwards compatibility with current usage.  The changes are:

 - Add enum ib_rate to midlayer includes.
 - Get rid of static rate translation in IPoIB; just use static rate
   directly from Path and MulticastGroup records.
 - Update mthca driver to translate absolute static rate into the
   format used by hardware.  This also fixes mthca's static rate
   handling for HCAs that are capable of 4X DDR.

Signed-off-by: Jack Morgenstein <jackm@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mthca/mthca_provider.h

@@ -257,6 +257,8 @@ struct mthca_qp {
 	atomic_t               refcount;
 	u32                    qpn;
 	int                    is_direct;
+	u8                     port; /* for SQP and memfree use only */
+	u8                     alt_port; /* for memfree use only */
 	u8                     transport;
 	u8                     state;
 	u8                     atomic_rd_en;
@@ -278,7 +280,6 @@ struct mthca_qp {
 
 struct mthca_sqp {
 	struct mthca_qp qp;
-	int             port;
 	int             pkey_index;
 	u32             qkey;
 	u32             send_psn;