sh: implement flush_icache_user_range

sh: implement flush_icache_user_range

The SuperH implementation of flush_icache_range seems to be able to cope
with user addresses.  Just define flush_icache_user_range to
flush_icache_range.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Link: http://lkml.kernel.org/r/20200515143646.3857579-22-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>