sh: export get_cpu_subtype

This patch fixes the following build error:

<--  snip  -->

...
  MODPOST 1837 modules
ERROR: "get_cpu_subtype" [arch/sh/oprofile/oprofile.ko] undefined!
...
make[2]: *** [__modpost] Error 1

<--  snip  -->
Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/setup.c

@@ -398,6 +398,7 @@ const char *get_cpu_subtype(struct sh_cpuinfo *c)
 {
 	return cpu_name[c->type];
 }
+EXPORT_SYMBOL(get_cpu_subtype);
 
 #ifdef CONFIG_PROC_FS
 /* Symbolic CPU flags, keep in sync with asm/cpu-features.h */