x86: fix dma_mapping_error for 32bit x86

Devices like b44 ethernet can't dma from addresses above 1GB. The driver
handles this cases by falling back to GFP_DMA allocation. But for detecting
the problem it needs to get an indication from dma_mapping_error.
The bug is triggered by using a VMSPLIT option of 2G/2G.

Signed-off-by: Thomas Bogendoerfer <[e-mail]>
Acked-by: FUJITA Tomonori <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/dma-mapping.h

···
 /* Make sure we keep the same behaviour */
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
-#ifdef CONFIG_X86_32
-	return 0;
-#else
+#ifdef CONFIG_X86_64
 	struct dma_mapping_ops *ops = get_dma_ops(dev);
 	if (ops->mapping_error)
 		return ops->mapping_error(dev, dma_addr);
 
-	return (dma_addr == bad_dma_address);
 #endif
+	return (dma_addr == bad_dma_address);
 }
 
 #define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)