Fixing bus_dma_tag_create(NULL, …).

[Edward Tomasz Napierała]

On sparc64, calling bus_dma_tag_create(9) with NULL tag will result in instant
panic due to KASSERT.  Patch below fixes all the instances I could find.  It also fixes
several places unrelated to sparc64, just to give a good example.

Now, the problem is - the changes are trivial and mechanical, but I have no way
to test most of it, simply because I don't have hardware handled by these drivers.
And I'm not really sure how to proceed from this point.  Any ideas?

Patch can be found at:

http://people.freebsd.org/~trasz/sparc64-bus_dma_tag_create.diff

-- 
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