Revert "tuna: set minimum brightness to 1 instead of 10"

Tuna doesn't look properly with this change. Screen is too dark for a normal use.

This reverts commit 1bc82a4162c2b7a56bad470797783dc37d54515c.

Change-Id: I2af2a10e4e26c2891f107720e661cdca173bdae5
Merge branch 'cm-10.2' into martincz