Keyguard: Don't apply input restriction if disabled by profile

setKeyguardEnabled() applies some input restrictions when disabling
the lockscreen. This causes issues when a system profile disables the
lockscreen via this method, e.g. the home button stops working until
a profile re-enables the lockscreen with setKeyguardEnabled(). If the
current profile is disabling keyguard, don't restrict the inputs.

BUGBASH-504

Change-Id: Iaaaabecaf19a18911d276a47f826dec3dec045c1