so it does not require a bounce buffer. The only need for this was
to align the buffer address. Implement unaligned access and we don't
need to copy data twice.
o Remove contigmalloc-based bounce buffer from xDMA code since it is
not suitable for arbitrary memory provided by platform, which is
sometimes a dedicated piece of memory that is not managed by OS at all.
Sponsored by: DARPA, AFRL
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