Sugov is a kernel thread used in ARM architecture as part of the scheduling governor.
the sugov kthread is a special RT task, which goal is just that to activate a frequency transition
As far as I can tell from the referenced documents the 13% CPU usage is a fake measurement and you needn't be worried about it.
It has a strange name so that grep can now easily find all its references in the kernel source without being overwhelmed by false matches.
References