RDMA/bnxt: Do not use ib_umem_page_count() or ib_umem_num_pages()

ib_umem_page_count() returns the number of 4k entries required for a DMA
map, but bnxt_re already computes a variable page size. The correct API to
determine the size of the page table array is ib_umem_num_dma_blocks().

Fix the overallocation of the page array in fill_umem_pbl_tbl() when
working with larger page sizes by using the right function. Lightly
re-organize this function to make it clearer.

Replace the other calls to ib_umem_num_pages().

Fixes: d8558251 ("RDMA/bnxt_re: Use core helpers to get aligned DMA address")
Link: https://lore.kernel.org/r/11-v2-270386b7e60b+28f4-umem_1_jgg@nvidia.com


Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>