Don't let apps disable the SIM PIN entry screen.

As the user (who controls the app behaviour after all) likely doesn't
see the PIN screen as a lock screen (he likely wants telephony) and the
PIN screen is not shown on a timer-driven basis, it should be treated
specially.

Change-Id: I3572a80d4a515d72e3aa4a6e933e980fa4516c2b
Don't start keyguard in an attempt to exit it.

exitKeyguardSecurely() will open the keyguard if it's currently disabled
by an app. As this is unwanted here (the user has either already
bypassed the keyguard or the keyguard isn't secure; otherwise he
couldn't click on a notification entry) and as the lockscreen already is
dismissed a few lines above, don't call exitKeyguardSecurely here.

Change-Id: I5582da350d8826e42f9edcd56845a59965865c8b
JIRA:CYAN-99