ARM: Replace platform definition of ISA_DMA_THRESHOLD/MAX_DMA_ADDRESS

The values of ISA_DMA_THRESHOLD and MAX_DMA_ADDRESS are related; one is
the physical/bus address, the other is the virtual address.  Both need
to be kept in step, so rather than having platforms define both, allow
them to define a single macro which sets both of these macros
appropraitely.

Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/dma.h b/arch/arm/include/asm/dma.h
index ca51143..4200554 100644
--- a/arch/arm/include/asm/dma.h
+++ b/arch/arm/include/asm/dma.h
@@ -6,8 +6,10 @@
 /*
  * This is the maximum virtual address which can be DMA'd from.
  */
-#ifndef MAX_DMA_ADDRESS
+#ifndef ARM_DMA_ZONE_SIZE
 #define MAX_DMA_ADDRESS	0xffffffff
+#else
+#define MAX_DMA_ADDRESS	(PAGE_OFFSET + ARM_DMA_ZONE_SIZE)
 #endif
 
 #ifdef CONFIG_ISA_DMA_API