tests: staging: sched_android: Ensure frequencies are sorted

Created by: qperret

Cpufreq's scaling_available_frequencies sysfs file does not guarantee any particular order for the frequencies. As such, on devices where they're not sorted in increasing order, the schedtune frequency test will fail to compute the right target frequency, leading to test failures.

Fix this by sorting the frequencies when necessary in sched_android.py.

Signed-off-by: Quentin Perret qperret@google.com