ARM: highbank: enable DMA zone for LPAE

Some devices are restricted to 32-bit DMA. Thus the platform dma_zone_size
needs to be set. Otherwise dma-mapping code is complaining, e.g.

calxedaxgmac fff50000.ethernet: coherent DMA mask 0xffffffff is smaller
than system GFP_DMA mask 0xffffffffffffffff

Signed-off-by: Andreas Herrmann <andreas.herrmann@calxeda.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
diff --git a/arch/arm/mach-highbank/Kconfig b/arch/arm/mach-highbank/Kconfig
index cd9fcb1..efe4961 100644
--- a/arch/arm/mach-highbank/Kconfig
+++ b/arch/arm/mach-highbank/Kconfig
@@ -18,3 +18,4 @@
 	select PL320_MBOX
 	select SPARSE_IRQ
 	select USE_OF
+	select ZONE_DMA if ARM_LPAE