msm: ipa: start TAG process only when needed

Start tag process before clocks are gated only when explicitly required.
TAG process should run only if data was send to IPA prior to clock gating.
This is done when an IPA consumer was resumed before and now clocks
need to be gated.

Change-Id: I3cb159cc4ea02014d2c882340a8be8387362317f
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Ravit Katzav <rkatzav@codeaurora.org>