Bump MODULE_VERSION to 5.2.1

Change-Id: I132c72934727f344f850d117a7663fcff9e0ec5e
Reviewed-by: Matti Paaso <matti.paaso@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Merge remote-tracking branch 'origin/release' into stable

Change-Id: Id23fc1705d026f3da5eb1a5f13f3e9aca368c7ed
Merge remote-tracking branch 'origin/release' into stable

Change-Id: Idfe43a75901cf1a29946245bed0956b1541de298