xtensa: implement flush_icache_user_range

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

[jcmvbkbc@gmail.com: fix flush_icache_user_range in noMMU configs]
  Link: http://lkml.kernel.org/r/20200525221556.4270-1-jcmvbkbc@gmail.comSigned-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Link: http://lkml.kernel.org/r/20200515143646.3857579-23-hch@lst.deSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/xtensa/include/asm/cacheflush.h

@@ -145,6 +145,8 @@ void local_flush_cache_page(struct vm_area_struct *vma,
 
 #endif
 
+#define flush_icache_user_range flush_icache_range
+
 /* Ensure consistency between data and instruction cache. */
 #define local_flush_icache_range(start, end)				\
 	do {								\