MIPS: use dma_direct_ops for coherent I/O

MIPS: use dma_direct_ops for coherent I/O

Switch the simple cache coherent architectures that don't require any
DMA address translation to dma_direct_ops.

We'll soon use at least parts of the direct DMA ops implementation for
all platforms, so select the symbol globally.

Signed-off-by: Christoph Hellwig <[email protected]>
Patchwork: https://patchwork.linux-mips.org/patch/19540/
Signed-off-by: Paul Burton <[email protected]>
Cc: Florian Fainelli <[email protected]>
Cc: David Daney <[email protected]>
Cc: Kevin Cernekee <[email protected]>
Cc: Jiaxun Yang <[email protected]>
Cc: Tom Bogendoerfer <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: [email protected]
Cc: [email protected]