After mm.h was removed from the asm-generic version of cacheflush.h,
s390 allyesconfig shows several warnings of the following nature:

  In file included from arch/s390/include/generated/asm/cacheflush.h:1,
                   from drivers/media/platform/omap3isp/isp.c:42:
  include/asm-generic/cacheflush.h:16:42: warning: 'struct mm_struct' declared inside parameter list will not be visible outside of this definition or declaration

As Geert and Laurent point out, this driver does not need this header in
the two files that include it.  Remove it so there are no warnings.

Link: http://lkml.kernel.org/r/20200622234740.72825-2-natechancellor@gmail.com
Fixes: e0cf615d725c ("asm-generic: don't include <linux/mm.h> in cacheflush.h")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>