power: supply: test_power: add missing newlines when printing parameters by sysfs

When I cat some module parameters by sysfs, it displays as follows.
It's better to add a newline for easy reading.

root@syzkaller:~# cd /sys/module/test_power/parameters/
root@syzkaller:/sys/module/test_power/parameters# cat ac_online
onroot@syzkaller:/sys/module/test_power/parameters# cat battery_present
trueroot@syzkaller:/sys/module/test_power/parameters# cat battery_health
goodroot@syzkaller:/sys/module/test_power/parameters# cat battery_status
dischargingroot@syzkaller:/sys/module/test_power/parameters# cat battery_technology
LIONroot@syzkaller:/sys/module/test_power/parameters# cat usb_online
onroot@syzkaller:/sys/module/test_power/parameters#
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/test_power.c

@@ -353,6 +353,7 @@ static int param_set_ac_online(const char *key, const struct kernel_param *kp)
 static int param_get_ac_online(char *buffer, const struct kernel_param *kp)
 {
 	strcpy(buffer, map_get_key(map_ac_online, ac_online, "unknown"));
+	strcat(buffer, "\n");
 	return strlen(buffer);
 }
 
@@ -366,6 +367,7 @@ static int param_set_usb_online(const char *key, const struct kernel_param *kp)
 static int param_get_usb_online(char *buffer, const struct kernel_param *kp)
 {
 	strcpy(buffer, map_get_key(map_ac_online, usb_online, "unknown"));
+	strcat(buffer, "\n");
 	return strlen(buffer);
 }
 
@@ -380,6 +382,7 @@ static int param_set_battery_status(const char *key,
 static int param_get_battery_status(char *buffer, const struct kernel_param *kp)
 {
 	strcpy(buffer, map_get_key(map_status, battery_status, "unknown"));
+	strcat(buffer, "\n");
 	return strlen(buffer);
 }
 
@@ -394,6 +397,7 @@ static int param_set_battery_health(const char *key,
 static int param_get_battery_health(char *buffer, const struct kernel_param *kp)
 {
 	strcpy(buffer, map_get_key(map_health, battery_health, "unknown"));
+	strcat(buffer, "\n");
 	return strlen(buffer);
 }
 
@@ -409,6 +413,7 @@ static int param_get_battery_present(char *buffer,
 					const struct kernel_param *kp)
 {
 	strcpy(buffer, map_get_key(map_present, battery_present, "unknown"));
+	strcat(buffer, "\n");
 	return strlen(buffer);
 }
 
@@ -426,6 +431,7 @@ static int param_get_battery_technology(char *buffer,
 {
 	strcpy(buffer,
 		map_get_key(map_technology, battery_technology, "unknown"));
+	strcat(buffer, "\n");
 	return strlen(buffer);
 }