m68k: dma: Remove unnecessary include of asm/cacheflush.h

In commit ca15ca40 ("mm: remove unneeded includes of
<asm/pgalloc.h>"), asm/cacheflush.h independent on the MACRO
was included at line 18. The include here is unnecessary. Remove it.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20210510030836.11834-1-wanjiabing@vivo.com


Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>