Fix handling of unavailable network in call barring activity.

Also remove some duplicated code.

Change-Id: I98aacd8b8f99824e8b0bd71fa140a6db3e8f4f00
Remove 'cancel all' preference.

It's functionally equivalent to setting incoming and outgoing call
barring to 'Off'.

Change-Id: I18c66cd54449aeb238e4da6fb5bb52d4375383ec
Add up navigation to call barring activity.

Change-Id: I0129f28bbdec280605a31f7ad35086ec970bf8f6