Recalculate emergency after adding or removing mobile controllers.

We might have shown 'emergency calls only' due to the lack of
controllers before [isEmergencyOnly() returns true if the voice sub
controller is missing], so make sure to properly hide it when adding
controllers.

TICKET: CRACKLING-410
Change-Id: Iad3762962f5d88df20599818b798cc0018e24e90
(cherry picked from commit d370ca53)