RDMA/efa: Use API to get contiguous memory blocks aligned to device supported page size
Use the ib_umem_find_best_pgsz() and rdma_for_each_block() API when
registering an MR instead of coding it in the driver.
ib_umem_find_best_pgsz() is used to find the best suitable page size
which replaces the existing efa_cont_pages() implementation.
rdma_for_each_block() is used to iterate the umem in aligned contiguous
memory blocks.