Revert "Fix default transparency value"

This reverts commit ca84547aed07b52a8cd5324573ec7ffd3d5cf3d3.

Change-Id: I57288de647835797bb84803ae7915750bb2d0a7b
SystemUI: fix default navigation bar transparency value

On a fresh flash the navigation bar was completely transparent.
Classic case of integer division, so cast one as a float to
resolve the issue.

Change-Id: I485346e9ac0e38ea68e8e9cf620f9fc455f1cc7a
Signed-off-by: Roman Birg <romanbirg@gmail.com>