powerpc: Remove the symbol __flush_icache_range

And now the function flush_icache_range() is just a wrapper which
only invoke the function __flush_icache_range() directly. So we
don't have reason to keep it anymore.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/misc_64.S

@@ -67,7 +67,7 @@ PPC64_CACHES:
  *   flush all bytes from start through stop-1 inclusive
  */
 
-_KPROBE(__flush_icache_range)
+_KPROBE(flush_icache_range)
 BEGIN_FTR_SECTION
 	blr
 END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)