LinuxKPI: pass attrs in more places in dma-mapping.h

Various macros (dma_map_sg_attrs, dma_unmap_sg_attrs,
dma_map_single_attrs, and dma_unmap_single_attrs) currently supress
passing on the attrs argument. Their implementation (even though at
times still marked the argument __unused; we remove that) have long
gained support for handling the argument.
With ofed fixed (5edf24aac1d09), pass the argument through so that
other drivers using these functions may hopefully work just a bit
better as well.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D55391