rust: dma: add missing __rust_helper annotations

The commit d893235 ("rust: dma: add helpers for architectures
without CONFIG_HAS_DMA") missed adding the __rust_helper annotations.
Add them.

Reported-by: Gary Guo <gary@garyguo.net>
Closes: https://lore.kernel.org/rust-for-linux/DFW4F5OSDO7A.TBUOX6RCN8G7@garyguo.net/
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260126071738.1670967-1-dirk.behme@de.bosch.com
[ Fix minor checkpatch.pl warning. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: dirkbehme

rust/helpers/dma.c

@@ -23,23 +23,23 @@ __rust_helper int rust_helper_dma_set_mask_and_coherent(struct device *dev,
 	return dma_set_mask_and_coherent(dev, mask);
 }
 
-int rust_helper_dma_set_mask(struct device *dev, u64 mask)
+__rust_helper int rust_helper_dma_set_mask(struct device *dev, u64 mask)
 {
 	return dma_set_mask(dev, mask);
 }
 
-int rust_helper_dma_set_coherent_mask(struct device *dev, u64 mask)
+__rust_helper int rust_helper_dma_set_coherent_mask(struct device *dev, u64 mask)
 {
 	return dma_set_coherent_mask(dev, mask);
 }
 
-int rust_helper_dma_map_sgtable(struct device *dev, struct sg_table *sgt,
-				enum dma_data_direction dir, unsigned long attrs)
+__rust_helper int rust_helper_dma_map_sgtable(struct device *dev, struct sg_table *sgt,
+					      enum dma_data_direction dir, unsigned long attrs)
 {
 	return dma_map_sgtable(dev, sgt, dir, attrs);
 }
 
-size_t rust_helper_dma_max_mapping_size(struct device *dev)
+__rust_helper size_t rust_helper_dma_max_mapping_size(struct device *dev)
 {
 	return dma_max_mapping_size(dev);
 }