Sibon: Use perf kernel

Fairphone OS is a sibon userdebug build, so make sure we focus at least
to some degree on performance and stability, rather than to open all
debug channels. Both debug kernel configs and enabling serial can have
significant impact on performance and stability in production usage.
Focus on ease of use instead, and let users build their own debug kernel
if they choose to do so.

Issue: FP2P-588
Change-Id: I941cca8838cd1b00567d6d9e54a9b2dfdeee3aff
2 files changed