[ARM] 5295/1: make ZONE_DMA optional

Most ARM machines don't need a special "DMA" memory zone, and
when configured out, the kernel becomes a bit smaller:

|   text    data     bss     dec     hex filename
|3826182  102384  111700 4040266  3da64a vmlinux
|3823593  101616  111700 4036909  3d992d vmlinux.nodmazone

This is because the system now has only one zone total which effect is
to optimize away many conditionals in page allocation paths.

So let's configure this zone only on machines that need split zones.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
index 3e07346..2e32acc 100644
--- a/arch/arm/common/Kconfig
+++ b/arch/arm/common/Kconfig
@@ -12,7 +12,8 @@
 
 config SA1111
 	bool
-	select DMABOUNCE
+	select DMABOUNCE if !ARCH_PXA
+	select ZONE_DMA if !ARCH_PXA
 
 config DMABOUNCE
 	bool