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: Lennox Wu <[e-mail]>
Signed-off-by: Chen Gang <[e-mail]>

arch/score/mm/cache.c

···
 		start += L1_CACHE_BYTES;
 	}
 }
+EXPORT_SYMBOL(flush_icache_range);