RDMA/efa: Use rdma block iterator in chunk list creation

When creating the chunks list the rdma_for_each_block() iterator is used
in order to iterate over the payload in EFA_CHUNK_PAYLOAD_SIZE (device
defined) strides.

Reviewed-by: Firas JahJah <firasj@amazon.com>
Reviewed-by: Yossi Leybovich <sleybo@amazon.com>
Reviewed-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Gal Pressman <galpress@amazon.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>