Rely on the dozeAmount changes for mIsDozing

The large clock view can be attached while the
doze transition is happening, so we don't want to
mistakently set mIsDozing=false from StatusBarStateController#isDozing
when we should be relying on the update from onDozeAmountChanged.

Test: manual
Fixes: 194277812
Change-Id: I202b9d845194f9d97d8ac1d6d1ff7e3f78491fd7