Pulled out part of onScreenTurnedOn() into show() function

The onScreenTurnedOn() function in LockPatternKeyguardView was
actually being called in two cases - when the screen was turned on,
AND when the show() function was called in KeyguardViewManager, which
actually happens just before the screen is turned off.  Face Unlock
functionality was added to the onScreenTurnedOn() function, not
expecting that the function was also being called just before the
screen turns off.  This causes Face Unlock to run when the screen is
turned off, preventing it from running when the screen is turned on.
This was not obvious during testing because it's not a problem when
testing from the lock screen.  To reproduce the problem you must log
in successfully, then turn the screen off, wait, and turn it back on.

The solution was to pull the non-face unlock functionality from
onScreenTurnedOn() into its own function called show(), which is
called from the KeyguardViewManager show() function and also called
from onScreenTurnedOn().  In this way, the onScreenTurnedOn()
functionality is not changed, but the show() function can be used
for the onScreenTurnedOn() functionality minus the Face Unlock stuff.

One exception to note - I left setting mScreenOn inside of
onScreenTurnedOn() and didn't pull it into show()...that seems like
the correct thing to do.

Change-Id: I9dcc144c7842112c4d35eb3f8b4ab1cd42c05675