power_supply: Add "unknown" in power supply type

For the default value of power supply type, "unknown" is added.
With default prop value, supply type property can be displayed
as default - "Unknown".

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
diff --git a/drivers/power/power_supply_sysfs.c b/drivers/power/power_supply_sysfs.c
index 58cc490..939e2e4 100644
--- a/drivers/power/power_supply_sysfs.c
+++ b/drivers/power/power_supply_sysfs.c
@@ -42,7 +42,7 @@
 					  struct device_attribute *attr,
 					  char *buf) {
 	static char *type_text[] = {
-		"Battery", "UPS", "Mains", "USB",
+		"Unknown", "Battery", "UPS", "Mains", "USB",
 		"USB_DCP", "USB_CDP", "USB_ACA"
 	};
 	static char *status_text[] = {