[ARM] Hide ISA DMA API when ISA_DMA_API is unset

When ISA_DMA_API is unset, we're not implementing the ISA DMA API,
so there's no point in publishing the prototypes via asm/dma.h, nor
including the machine dependent parts of that API.

This allows us to remove a lot of mach/dma.h files which don't contain
any useful code.  Unfortunately though, some platforms put their own
private non-ISA definitions into mach/dma.h, so we leave these behind
and fix the appropriate #include statments.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/dma.h

@@ -1,13 +1,7 @@
 #ifndef __ASM_ARM_DMA_H
 #define __ASM_ARM_DMA_H
 
-typedef unsigned int dmach_t;
-
-#include <linux/spinlock.h>
 #include <asm/memory.h>
-#include <asm/system.h>
-#include <asm/scatterlist.h>
-#include <mach/dma.h>
 
 /*
  * This is the maximum virtual address which can be DMA'd from.
@@ -16,6 +10,19 @@ typedef unsigned int dmach_t;
 #define MAX_DMA_ADDRESS	0xffffffff
 #endif
 
+#ifdef CONFIG_ISA_DMA_API
+/*
+ * This is used to support drivers written for the x86 ISA DMA API.
+ * It should not be re-used except for that purpose.
+ */
+#include <linux/spinlock.h>
+#include <asm/system.h>
+#include <asm/scatterlist.h>
+
+typedef unsigned int dmach_t;
+
+#include <mach/dma.h>
+
 /*
  * DMA modes
  */
@@ -141,4 +148,6 @@ extern int isa_dma_bridge_buggy;
 #define isa_dma_bridge_buggy    (0)
 #endif
 
-#endif /* _ARM_DMA_H */
+#endif /* CONFIG_ISA_DMA_API */
+
+#endif /* __ASM_ARM_DMA_H */