IB/ipath: User mode send DMA

A new file which allows the IBA7220 send DMA engine to be used from
userland.  The routines here are not linked in yet, that will happen in
a follow-on patch...
Signed-off-by: NArthur Jones <arthur.jones@qlogic.com>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>