bnxt_en: Fix context memory allocation.

When allocating memory pages for context memory, if the last page table
should be fully populated, the current code will set nr_pages to 0 when
calling bnxt_alloc_ctx_mem_blk().  This will cause the last page table
to be completely blank and causing some RDMA failures.

Fix it by setting the last page table's nr_pages to the remainder only
if it is non-zero.

Fixes: 08fe9d1 ("bnxt_en: Add Level 2 context memory paging support.")
Reported-by: Eric Davis <eric.davis@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -6222,9 +6222,12 @@ static int bnxt_alloc_ctx_pg_tbls(struct bnxt *bp,
 			rmem->pg_tbl_map = ctx_pg->ctx_dma_arr[i];
 			rmem->depth = 1;
 			rmem->nr_pages = MAX_CTX_PAGES;
-			if (i == (nr_tbls - 1))
-				rmem->nr_pages = ctx_pg->nr_pages %
-						 MAX_CTX_PAGES;
+			if (i == (nr_tbls - 1)) {
+				int rem = ctx_pg->nr_pages % MAX_CTX_PAGES;
+
+				if (rem)
+					rmem->nr_pages = rem;
+			}
 			rc = bnxt_alloc_ctx_mem_blk(bp, pg_tbl);
 			if (rc)
 				break;