MIPS: dma-default: Don't check hw_coherentio if device is non-coherent

MIPS: dma-default: Don't check hw_coherentio if device is non-coherent

There are no cases where plat_device_is_coherent() will return zero
whilst hw_coherentio is non-zero, and acting any differently in such a
case doesn't make much sense - if a device is non-coherent with the CPU
caches then access to memory "coherent" with DMA must be uncached. Clean
up the nonsensical case.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14348/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>