power: supply: test-power: use strscpy() instead of strncpy()

The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL-terminated strings.
Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/test_power.c

@@ -306,8 +306,7 @@ static int map_get_value(struct battery_property_map *map, const char *key,
 	char buf[MAX_KEYLENGTH];
 	int cr;
 
-	strncpy(buf, key, MAX_KEYLENGTH);
-	buf[MAX_KEYLENGTH-1] = '\0';
+	strscpy(buf, key, MAX_KEYLENGTH);
 
 	cr = strnlen(buf, MAX_KEYLENGTH) - 1;
 	if (cr < 0)