msm: ipa: debugfs: Update keep_awake to use PM APIs

Update the keep_awake script to call into IPA PM and
add/remove dummy clients to change the clk vote dynamically
based on the loaded device's power thresholds.

Change-Id: Ifaa4ef1e312428245605008998ac59afddf09d99
Signed-off-by: Michael Adisumarta <madisuma@codeaurora.org>