Remove top margin from dream status bar items

This change removes the static vertical margins that cause a
misalignment with other dream status bar items.

Bug: 288467787
Fix: 288467787
Test: https://screenshot.googleplex.com/C9UyHNeY95E956J
(cherry picked from commit 57ae5bac)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:88d0e75d521248768391c3aa6b1630d607577025)
Merged-In: I64c45f09d4e9a5fd78ef0277def70c912421b5ad
Change-Id: I64c45f09d4e9a5fd78ef0277def70c912421b5ad