Set expected pin length in constructor.

In the bug, it seems clear that the pinlength field is set to 0. This
means that the start appar animation is not called here but the view is
inflated...Having the field at 0 is causing an ANR. I believe this is
likely because we are calling reset somewhere before we show the view.

Test: Open bouncer and authenticate auto confirmation pin bouncer.
Fixes: 281424496
Change-Id: I776645ea633e49e45e8e30386cfc91bff3339f72