msm: dcvs: force on the slack timer

For performance reasons the kernel should execute
a ONLINE call on TZ when the governor starts. The return
 values from ONLINE call are a new frequency and a new
 slack timer.

This new frequency would be queued up for the thread to set it up
on that core.

The way we handle the new slack timer is interesting. When the
governor starts we really dont know what the state of idle pulses
is, this is indicated by setting idle_entered = -1.  However we
want to start the slack timer. To handle this situation create
a function to force on the hrtimer without checking idle_entered or
pending_freq.

Change-Id: I5aeae15a697b36b55716906616147549c3f46202
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>