[ARM] fix constant values of MAX_DMA_ADDRESS

Since 8d5796d2, we have allowed
PAGE_OFFSET to be configurable, so a constant virtual address
for MAX_DMA_ADDRESS is buggy.  It should be defined in terms of
PAGE_OFFSET rather than a constant virtual address.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-h720x/include/mach/memory.h

@@ -16,6 +16,6 @@
  * If you set this, you must also set ISA_DMA_THRESHOLD and setup a DMA
  * zone if this does not cover all possible RAM.
  */
-#define MAX_DMA_ADDRESS		0xd0000000
+#define MAX_DMA_ADDRESS		(PAGE_OFFSET + SZ_256M)
 
 #endif

arch/arm/mach-s3c2410/include/mach/memory.h

@@ -13,12 +13,4 @@
 
 #define PHYS_OFFSET	UL(0x30000000)
 
-/*
- * This is the maximum DMA address(physical address) that can be DMAd to.
- *  Err, no, this is a virtual address.  And you must set ISA_DMA_THRESHOLD
- *  and setup a DMA zone if this restricts the amount of RAM which is
- *  capable of DMA.
- */
-#define MAX_DMA_ADDRESS		0x40000000
-
 #endif

arch/arm/mach-shark/include/mach/memory.h

@@ -33,7 +33,7 @@ static inline void __arch_adjust_zones(int node, unsigned long *zone_size, unsig
 	__arch_adjust_zones(node, size, holes)
 
 #define ISA_DMA_THRESHOLD	(PHYS_OFFSET + SZ_4M - 1)
-#define MAX_DMA_ADDRESS		0xC0400000
+#define MAX_DMA_ADDRESS		(PAGE_OFFSET + SZ_4M)
 
 #endif