Currently the last found MCC is reconfigured only in the recovery flow.
But it should always be used when available, for the ifdown/up or
RF-Kill/CT-Kill scenarios.
While at it, fix a couple of bugs in the init-from-last-MCC flow. Return
an error value when a current MCC is not found. Pass on the regdomain to
cfg80211 only if it was changed and don't ignore the return value from
the cfg80211-setter function.