kallsyms: fix building without printk

Building kallsyms fails without CONFIG_PRINTK due to a missing
declaration:

  kernel/kallsyms.c: In function 'kallsyms_show_value':
  kernel/kallsyms.c:670:10: error: 'kptr_restrict' undeclared (first use in this function); did you mean 'keyring_restrict'?

This moves the declaration outside of the #ifdef guard, the definition
is already available without CONFIG_PRINTK.

Fixes: c0f3ea158939 ("stop using '%pK' for /proc/kallsyms pointer values")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[ I clearly need to start doing "allnoconfig" builds too, or just have a
  test branch for the 0day robot - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/printk.h

@@ -189,7 +189,6 @@ extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 
 extern int printk_delay_msec;
 extern int dmesg_restrict;
-extern int kptr_restrict;
 
 extern int
 devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, void __user *buf,
@@ -280,6 +279,8 @@ static inline void printk_safe_flush_on_panic(void)
 }
 #endif
 
+extern int kptr_restrict;
+
 extern asmlinkage void dump_stack(void) __cold;
 
 #ifndef pr_fmt