RDMA/umem: Add rdma_umem_for_each_dma_block()

This helper does the same as rdma_for_each_block(), except it works on a
umem. This simplifies most of the call sites.

Link: https://lore.kernel.org/r/4-v2-270386b7e60b+28f4-umem_1_jgg@nvidia.com
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
diff --git a/.clang-format b/.clang-format
index a0a9608..311ef2c 100644
--- a/.clang-format
+++ b/.clang-format
@@ -415,6 +415,7 @@
   - 'rbtree_postorder_for_each_entry_safe'
   - 'rdma_for_each_block'
   - 'rdma_for_each_port'
+  - 'rdma_umem_for_each_dma_block'
   - 'resource_list_for_each_entry'
   - 'resource_list_for_each_entry_safe'
   - 'rhl_for_each_entry_rcu'