Prevent uses of all dual display states with an external display

Some time ago, DEVICE_STATE_REAR_DISPLAY_OUTER_DEFAULT was introduced
with is also a dual display state. First, performance wise, most phones
don't support that many local displays. Second, a lot of code assume
this isn't possible.

Fix: 445146126
Test: atest BookStyleDeviceStatePolicyTest
Test: manual with Google Camera
Flag: EXEMPT BUGFIX
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:a90d0f0e7b029134b602880ccd163440ab634737
Merged-In: Ib520b8e62bcff31ae2352d4b6421969158b46ccc
Change-Id: Ib520b8e62bcff31ae2352d4b6421969158b46ccc