cpufreq: interactive: handle speed up and down in the realtime task

Not useful to have a separate, non-realtime workqueue for speed down
events, avoid priority inversion for speed up events.

Change-Id: Iddcd05545245c847aa1bbe0b8790092914c813d2
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Git-Commit: f8aa05d96a0d18416d2627c493f7dc9bc5324901
Git-Repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Dilip Gudlur <dgudlur@codeaurora.org>