cpufreq: interactive: Make it compile for v4.9

cpufreq_frequency_table_target() returns the index now so change
the calling convention. Also the governor start/stop enum switch
statement design has been replaced with named function callbacks,
so split up the code and change it for that as well.

Change-Id: I946cbb98aa7f82bf28691d87cfbfd879f0e475a4
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>