powerpc/dma: dma_set_coherent_mask() should not be GPL only

When turning this from inline to an exported function I was a bit
over-eager and made it GPL only. This prevents the use of pretty much
all non-GPL PCI driver which is a bit over the top. Let's bring it
back in line with other architecture.

Fixes: 817820b0 ("powerpc/iommu: Support "hybrid" iommu/direct DMA ops for coherent_mask < dma_mask")
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/dma.c

@@ -303,7 +303,7 @@ int dma_set_coherent_mask(struct device *dev, u64 mask)
 	dev->coherent_dma_mask = mask;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(dma_set_coherent_mask);
+EXPORT_SYMBOL(dma_set_coherent_mask);
 
 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)