use generic DMA mapping code in powerpc V4

[Christoph Hellwig]

On Thu, Dec 13, 2018 at 12:19:26PM +0100, Christian Zigotzky wrote:
> I tried it again but I get the following error message:
>
> MODPOST vmlinux.o
> arch/powerpc/kernel/dma-iommu.o: In function `.dma_iommu_get_required_mask':
> (.text+0x274): undefined reference to `.dma_direct_get_required_mask'
> make: *** [vmlinux] Error 1

Sorry, you need this one liner before all the patches posted last time:

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d8819e3a1eb1..7e78c2798f2f 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -154,6 +154,7 @@ config PPC
 	select CLONE_BACKWARDS
 	select DCACHE_WORD_ACCESS		if PPC64 && CPU_LITTLE_ENDIAN
 	select DYNAMIC_FTRACE			if FUNCTION_TRACER
+	select DMA_DIRECT_OPS
 	select EDAC_ATOMIC_SCRUB
 	select EDAC_SUPPORT
 	select GENERIC_ATOMIC64			if PPC32