ANDROID: cpufreq: create dummy cpufreq driver

/proc/uid_time_in_state has no data on cuttlefish because its cpu
frequency tables are empty. Because time in state & concurrent time
accounting are intertwined this causes the
/proc/uid_concurrent_{policy,active}_time files to also not contain
any data.

Add a minimal, fake cpufreq driver that creates a freq table with 2
frequencies per policy, to allow testing time in state functionality.

Test: all 3 proc files show reasonable data on cuttlefish
Test: log shows no errors from bad /proc/uid_time_in_state format
Bug: 139763108
Bug: 140796321
Bug: 141206930
Change-Id: I8c7fe1007a80c21a9bcba9455bf837947cf42963
Signed-off-by: Connor O'Brien <connoro@google.com>