arm: rename flush_cache_user_range to flush_icache_user_range

flush_icache_user_range will be the name for a generic primitive.  Move
the arm name so that arm already has an implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Link: http://lkml.kernel.org/r/20200515143646.3857579-24-hch@lst.de


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>