Include subQuality when returning from EncryptionInterstitial

When a device is encrypted and the user selects fingerprint as the
unlock method, the user would be presented with instructions about
using face unlock instead of proceeding with setting up a fingerprint.

This patch stores the subQuality in a member variable which can then
be used to determine which screen to show next.

Change-Id: Ie3f26917a27c7eabb96430646b69775d014b2db2
REF: CYNGNOS-664
(cherry picked from commit 2677fb5c)