cpufreq: interactive: apply intermediate load to max speed not current

Evaluate spikes in load (below go_hispeed_load) against the maximum
speed supported by the device, not the current speed (which tends to
make it too difficult to raise speed to intermediate levels until
very busy).

Change-Id: Ib937006abf8bedb60891a739acd733e89b732ae0
Signed-off-by: Todd Poynor <toddpoynor@google.com>