ARM: fix IXP4xx build failure

arm: export dma_set_coherent_mask

While a regression was fixed with commit 710224fa (arm: fix
"arm: fix pci_set_consistent_dma_mask for dmabounce devices"), a
new one was introduced as dma_set_coherent_mask wasn't exported
for modules. This patch takes care for this issue.
Signed-off-by: NImre Kaloz <kaloz@openwrt.org>
Signed-off-by: NKrzysztof Hałasa <khc@pm.waw.pl>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/arm/common/it8152.c

@@ -352,3 +352,4 @@ struct pci_bus * __init it8152_pci_scan_bus(int nr, struct pci_sys_data *sys)
 	return pci_scan_bus(nr, &it8152_ops, sys);
 }
 
+EXPORT_SYMBOL(dma_set_coherent_mask);

arch/arm/mach-ixp4xx/common-pci.c

@@ -513,4 +513,4 @@ int dma_set_coherent_mask(struct device *dev, u64 mask)
 
 EXPORT_SYMBOL(ixp4xx_pci_read);
 EXPORT_SYMBOL(ixp4xx_pci_write);
-
+EXPORT_SYMBOL(dma_set_coherent_mask);