revert dma direct internals abuse

Christoph Hellwig
2019-04-08T10:55:50Z

Hi Linus,

unfortunately it took less than a merge window for the:

/*
* All the dma_direct_* declarations are here just for the indirect call bypass,
* and must not be used directly drivers!
*/

warning in dma-mapping.h to be ignored. This series reverts the offender
to keep our API clean.

Thomas: please talk me first about your needs and I'll be happy to figure out
a proper API for what you want to do.