Fix the mfd device in the case where a subdevice might not be activated.
Signed-off-by: NPantelis Antoniou <panto@antoniou-consulting.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>