cpufreq: interactive: run at fraction of hispeed_freq when load is low

When load is below go_hispeed_load, apply the percentage of CPU load to
a max frequency of hispeed_freq instead of the max speed.  This avoids
jumping too quickly to hispeed_freq when it is a relatively low
percentage of max speed.  This also allows go_hispeed_load to be set to
a high percentage relative to hispeed_freq (as a percentage of max speed,
again useful when hispeed_freq is a low fraction of max speed), to cap
larger loads at hispeed_freq.  For example, a load of 60% will typically
move to 60% of hispeed_freq, not 60% of max speed.  This causes the
governor to apply two different speed caps, depending on whether load is
below or above go_hispeed_load.

Also fix the type of hispeed_freq, which was u64, to match other
speed data types (and avoid overhead and allow division).

Change-Id: Ie2d0668be161c074aaad77db2037505431457b3a
Signed-off-by: Todd Poynor <toddpoynor@google.com>