Don't do anti-falsing on locked shade

The user has already passed the keyguard test by
dragging down. We're not doing anti falsing at this
point and doing it on the affordance was triggering
a crash on debuggable builds (and not working at all
on regular builds).

Change-Id: Icaf81e8e2a38503851c7b5699a0f5a3d363dac19
Fixes: 28154836