cpuset: Force nice=10 for background tasks

* Android use 10 by default. It makes no sense for oneplus to use 0
* This could reserve more cpu for non-background tasks

Change-Id: I625deac43c865a6342de47619a571e5e8b0e2421
Signed-off-by: minaripenguin <minaripenguin@users.noreply.github.com>