powerpc/dma: fix an off-by-one in dma_capable

We need to compare the last byte in the dma range and not the one after it
for the bus_dma_mask, just like we do for the regular dma_mask.  Fix this
cleanly by merging the two comparisms into one.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/dma-direct.h

@@ -4,15 +4,11 @@
 
 static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 {
-#ifdef CONFIG_SWIOTLB
-	if (dev->bus_dma_mask && addr + size > dev->bus_dma_mask)
-		return false;
-#endif
-
 	if (!dev->dma_mask)
 		return false;
 
-	return addr + size - 1 <= *dev->dma_mask;
+	return addr + size - 1 <=
+		min_not_zero(*dev->dma_mask, dev->bus_dma_mask);
 }
 
 static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)