cpufreq: interactive: Move definition of cpufreq_gov_interactive down…
…wards

This moves definition of cpufreq_gov_interactive towards the bottom of file, so
that we don't have to add prototype of cpufreq_governor_interactive() in the
beginning of file.

Change-Id: I04bd1004954eb36502c5cd7e35d3d7274cddaf95

[also tidied up abit]