m68k: implement flush_icache_user_range

m68k: implement flush_icache_user_range

Rename the current flush_icache_range to flush_icache_user_range as per
commit f0d41414d008 ("PATCH] flush icache in correct context") there
seems to be an assumption that it operates on user addresses.  Add a
flush_icache_range around it that for now is a no-op.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Link: http://lkml.kernel.org/r/20200515143646.3857579-25-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>