linuxkpi: Add dma_{un,}map_sgtable

[manu]

Summary

Variant of dma_{un,}map_sg_attrs for struct sg_table.

Obtained from: drm-kmod
Sponsored by: Beckhoff Automation GmbH & Co. KG

[bz]

sys/compat/linuxkpi/common/include/linux/dma-mapping.h

360

Shouldn't this here be dma_unmap_sg_attrs with the attrs passed in (even though it's later ignored) so in case our version will ever respect "attrs" it'll do the right thing here already?

[manu]

Use dma_unmap_sg_attrs in dma_unmap_sgtable