ARM: ensure tag tables are const

Nothing should ever modify a tag table entry, so mark these const.
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/setup.h

@@ -187,7 +187,7 @@ struct tagtable {
 
 #define __tag __used __attribute__((__section__(".taglist.init")))
 #define __tagtable(tag, fn) \
-static struct tagtable __tagtable_##fn __tag = { tag, fn }
+static const struct tagtable __tagtable_##fn __tag = { tag, fn }
 
 /*
  * Memory map description