cpufreq: Add a boostpulse interface to ondemand

For applications that require a one-shot increase in frequency,
the boostpulse interface would help to scale to max for the time
specified in boostime. This helps applications that currently
increases scaling_min_freq and resets later after a fixed duration.
Instead of changing scaling_min_freq applications can directly write
to boostpulse and governer resets during regular timer after the time
expires.

Change-Id: I5b418f8b2d4eb38ea0684bbb5054f3234c60d4c0
Signed-off-by: Narayanan Gopalakrishnan <nargop@codeaurora.org>
Signed-off-by: RonGokhale <cips173@gmail.com>