dma-direct: we might need GFP_DMA for 32-bit dma masks

If there is no ZONE_DMA32 we might need GFP_DMA to be able to
allocate memory that satisfies a 32-bit DMA mask.

Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

kernel/dma/direct.c

@@ -132,8 +132,7 @@ again:
 			goto again;
 		}
 
-		if (IS_ENABLED(CONFIG_ZONE_DMA) &&
-		    phys_mask < DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) {
+		if (IS_ENABLED(CONFIG_ZONE_DMA) && !(gfp & GFP_DMA)) {
 			gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
 			goto again;
 		}