arch/score/mm/cache.c: Export 'flush_icache_range'

The related error (with allmodconfig under score):

    MODPOST 1365 modules
  ERROR: "flush_icache_range" [drivers/misc/lkdtm.ko] undefined!
Acked-by: NLennox Wu <lennox.wu@gmail.com>
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>

arch/score/mm/cache.c

@@ -278,3 +278,4 @@ void flush_icache_range(unsigned long start, unsigned long end)
 		start += L1_CACHE_BYTES;
 	}
 }
+EXPORT_SYMBOL(flush_icache_range);