m68k: merge mmu and non-mmu versions of dma.h

The non-mmu version of dma.h contains a lot of ColdFire specific DMA
support, but also all of the base m68k support. So use the non-mmu
version of dma.h for all.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>

arch/m68k/include/asm/dma_mm.h

-#ifndef _M68K_DMA_H
-#define _M68K_DMA_H 1
-
-
-/* it's useless on the m68k, but unfortunately needed by the new
-   bootmem allocator (but this should do it for this) */
-#define MAX_DMA_ADDRESS PAGE_OFFSET
-
-#define MAX_DMA_CHANNELS 8
-
-extern int request_dma(unsigned int dmanr, const char * device_id);	/* reserve a DMA channel */
-extern void free_dma(unsigned int dmanr);	/* release it again */
-
-#define isa_dma_bridge_buggy    (0)
-
-#endif /* _M68K_DMA_H */