RDMA/bnxt_re: Fix an IS_ERR() vs NULL check

The bnxt_re_mmap_entry_insert() function returns NULL, not error pointers.
Update the check for errors accordingly.

Fixes: 360da60 ("RDMA/bnxt_re: Enable low latency push")
Link: https://lore.kernel.org/r/8d92e85f-626b-4eca-8501-ca7024cfc0ee@moroto.mountain
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: Dan Carpenter

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -4214,8 +4214,8 @@ static int UVERBS_HANDLER(BNXT_RE_METHOD_ALLOC_PAGE)(struct uverbs_attr_bundle *
 	}
 
 	entry = bnxt_re_mmap_entry_insert(uctx, dbr, mmap_flag, &mmap_offset);
-	if (IS_ERR(entry))
-		return PTR_ERR(entry);
+	if (!entry)
+		return -ENOMEM;
 
 	uobj->object = entry;
 	uverbs_finalize_uobj_create(attrs, BNXT_RE_ALLOC_PAGE_HANDLE);