iw_cxgb4: allocate wait object for each memory object

Remove the local stack allocated c4iw_wr_wait object in preparation for
correctly handling timeouts.

Also refactored some code to simplify it and make errpath unwinding
more readable.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/cxgb4/iw_cxgb4.h

@@ -394,6 +394,7 @@ struct c4iw_mr {
 	dma_addr_t mpl_addr;
 	u32 max_mpl_len;
 	u32 mpl_len;
+	struct c4iw_wr_wait *wr_waitp;
 };
 
 static inline struct c4iw_mr *to_c4iw_mr(struct ib_mr *ibmr)
@@ -407,6 +408,7 @@ struct c4iw_mw {
 	struct sk_buff *dereg_skb;
 	u64 kva;
 	struct tpt_attributes attr;
+	struct c4iw_wr_wait *wr_waitp;
 };
 
 static inline struct c4iw_mw *to_c4iw_mw(struct ib_mw *ibmw)