msm: ipa4: IPA PM Unit tests

Unit test for testing basic functionality of the IPA PM. It goes over all
the new APIs of the PM + some common usecases and checks if the
intended behavior is shown.

Change-Id: If1bc33c5ab00b384b94d62106399570f61114f63
CRs-Fixed: 2097404
Signed-off-by: Michael Adisumarta <madisuma@codeaurora.org>