ACPI / sysfs: Make function param_set_trace_method_name() static

The function param_set_trace_method_name is local to the source and does
not need to be in global scope, so make it static.

Cleans up sparse warning:
symbol 'param_set_trace_method_name' was not declared. Should it be static?
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sysfs.c

@@ -169,7 +169,8 @@ module_param_cb(debug_level, &param_ops_debug_level, &acpi_dbg_level, 0644);
 
 static char trace_method_name[1024];
 
-int param_set_trace_method_name(const char *val, const struct kernel_param *kp)
+static int param_set_trace_method_name(const char *val,
+				       const struct kernel_param *kp)
 {
 	u32 saved_flags = 0;
 	bool is_abs_path = true;