generic/dma-mapping.h: remove BUG_ON flags not GFP_ATOMIC

drivers should always check for a NULL return anyway, so the fact
that the pci_ API is GFP_ATOMIC shouldn't matter.

include/asm-generic/dma-mapping.h

@@ -33,7 +33,7 @@ static inline void *
 dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 		   int flag)
 {
-	BUG_ON(dev->bus != &pci_bus_type || (flag & GFP_ATOMIC) != GFP_ATOMIC);
+	BUG_ON(dev->bus != &pci_bus_type);
 
 	return pci_alloc_consistent(to_pci_dev(dev), size, dma_handle);
 }