Fix the following sparse warnings for un-declared variables
by making them static:

kernel/hung_task.c:31:19: warning: symbol 'sysctl_hung_task_check_count' was not declared. Should it be static?
kernel/hung_task.c:50:29: warning: symbol 'sysctl_hung_task_check_interval_secs' was not declared. Should it be static?
kernel/hung_task.c:52:19: warning: symbol 'sysctl_hung_task_warnings' was not declared. Should it be static?
kernel/hung_task.c:75:28: warning: symbol 'sysctl_hung_task_panic' was not declared. Should it be static?

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
---
 kernel/hung_task.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index bb2354f73ded..48106a950554 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -28,7 +28,7 @@
 /*
  * The number of tasks checked:
  */
-int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
+static int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
 
 /*
  * Limit number of tasks checked in a batch.
@@ -47,9 +47,9 @@ unsigned long __read_mostly sysctl_hung_task_timeout_secs = CONFIG_DEFAULT_HUNG_
 /*
  * Zero (default value) means use sysctl_hung_task_timeout_secs:
  */
-unsigned long __read_mostly sysctl_hung_task_check_interval_secs;
+static unsigned long __read_mostly sysctl_hung_task_check_interval_secs;
 
-int __read_mostly sysctl_hung_task_warnings = 10;
+static int __read_mostly sysctl_hung_task_warnings = 10;
 
 static int __read_mostly did_panic;
 static bool hung_task_show_lock;
@@ -72,7 +72,7 @@ static unsigned int __read_mostly sysctl_hung_task_all_cpu_backtrace;
  * Should we panic (and reboot, if panic_timeout= is set) when a
  * hung task is detected:
  */
-unsigned int __read_mostly sysctl_hung_task_panic =
+static unsigned int __read_mostly sysctl_hung_task_panic =
 				IS_ENABLED(CONFIG_BOOTPARAM_HUNG_TASK_PANIC);
 
 static int
-- 
2.35.1