Fix changing password

chpasswd was missing and then it had a wrong path.

Change-Id: Idc67dde22cc1f28b3780b4c434df80bdb3ab6014
diff --git a/board/czechlight/common/busybox-config b/board/czechlight/common/busybox-config
index 174c853..1a4f03d 100644
--- a/board/czechlight/common/busybox-config
+++ b/board/czechlight/common/busybox-config
@@ -8,3 +8,6 @@
 
 # initial flashing
 CONFIG_BLKDISCARD=y
+
+# velia-system password change
+CONFIG_CHPASSWD=y