Avoid binder call during ContextImple#updateResourceOverlayConstraints

ContextImpl#updateResourceOverlayConstraints requires displayId and
deviceId. We were fetching displayId using ContextImpl#getDisplay,
which makes a binder call into DisplayManagerService if the relevant
DisplayInfo is not cached in DisplayManagerGlobal. This change avoids
calling ContextImpl#getDisplay and calculates the displayId using
mDisplay member directly.

Test: atest OverlayConstraintsTests
Fixes: 398926802
Flag: EXEMPT bugfix
Change-Id: I269bacc5050c018da5da7b6eb979c4687645efd9