msm: ipa: suspend apps endpoint on clock gating

Before going to clock gating suspend all IPA apps pipes.
In case a packet arrives to apps while apps voted for IPA clock
gating, a suspend interrupt will be fired and IPA clocks will be voted.

Change-Id: I1fb22ede33c09032ec63106c9d04de3b08dff5b2
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>