[RFC PATCH] battery: hook_mutex can be static

[kbuild test robot <lkp@xxxxxxxxx>]

Fixes: 19380b8e214c ("battery: Add the battery hooking API")
Signed-off-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
---
 battery.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 1794408..9324591 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -640,9 +640,9 @@ static const struct device_attribute alarm_attr = {
 
 LIST_HEAD(acpi_battery_list);
 LIST_HEAD(battery_hook_list);
-DEFINE_MUTEX(hook_mutex);
+static DEFINE_MUTEX(hook_mutex);
 
-void __battery_hook_unregister(struct acpi_battery_hook *hook, int force)
+static void __battery_hook_unregister(struct acpi_battery_hook *hook, int force)
 {
 	struct list_head *position;
 	struct acpi_battery *battery;