printk: Fix incorrect __user type in proc_dointvec_minmax_sysadmin()

The move of proc_dointvec_minmax_sysadmin() from kernel/sysctl.c to
kernel/printk/sysctl.c introduced an incorrect __user attribute to the
buffer argument.  I spotted this change in [1] as well as the kernel
test robot.  Revert this change to please sparse:

  kernel/printk/sysctl.c:20:51: warning: incorrect type in argument 3 (different address spaces)
  kernel/printk/sysctl.c:20:51:    expected void *
  kernel/printk/sysctl.c:20:51:    got void [noderef] __user *buffer

Fixes: faaa357 ("printk: move printk sysctl to printk/sysctl.c")
Link: https://lore.kernel.org/r/[email protected] [1]
Reported-by: kernel test robot <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: John Ogness <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Xiaoming Ni <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

kernel/printk/sysctl.c

@@ -12,7 +12,7 @@
 static const int ten_thousand = 10000;
 
 static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
-				void __user *buffer, size_t *lenp, loff_t *ppos)
+				void *buffer, size_t *lenp, loff_t *ppos)
 {
 	if (write && !capable(CAP_SYS_ADMIN))
 		return -EPERM;