RDMA/qedr: Use ib_umem_num_dma_blocks() instead of ib_umem_page_count()

The length of the list populated by qedr_populate_pbls() should be
calculated using ib_umem_num_dma_blocks() with the same size/shift passed
to qedr_populate_pbls().

Link: https://lore.kernel.org/r/10-v2-270386b7e60b+28f4-umem_1_jgg@nvidia.com


Acked-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>