m68k: use the coherent DMA code for coldfire without data cache

Coldfire cores configured without a data cache are DMA coherent and
should thus simply use the simple coherent version of dma-direct.

Introduce a new COLDFIRE_COHERENT_DMA Kconfig symbol as a convenient
short hand for such configurations, and a M68K_NONCOHERENT_DMA symbol
for all cases where we need to build non-coherent DMA infrastructure
to simplify the Kconfig and code conditionals.

Not building the non-coherent DMA code slightly reduces the code
size for such configurations.

Numers for m5249evb_defconfig below:

  text	   data	    bss	    dec	    hex	filename
2896158	 401052	  65392	3362602	 334f2a	vmlinux.before
2895166	 400988	  65392	3361546	 334b0a	vmlinux.after

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Greg Ungerer <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Tested-by: Greg Ungerer <[email protected]>

0 files changed, 0 insertions, 0 deletions