Add support to register a memory with the firmware via the DEVX
interface.

The driver translates a given user address to ib_umem then it will
register the physical addresses with the firmware and get a unique id
for this registration to be used for this virtual address.
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>