[ARM] dmabounce requires ZONE_DMA

Rather than having everything that needs DMABOUNCE also select
ZONE_DMA, arrange for DMABOUNCE to select it instead.  This is
far more sensible.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
index 2e32acc..86b5e69 100644
--- a/arch/arm/common/Kconfig
+++ b/arch/arm/common/Kconfig
@@ -13,10 +13,10 @@
 config SA1111
 	bool
 	select DMABOUNCE if !ARCH_PXA
-	select ZONE_DMA if !ARCH_PXA
 
 config DMABOUNCE
 	bool
+	select ZONE_DMA
 
 config TIMER_ACORN
 	bool