msm: ipa: GSI coalescing changes

Add new struct for GCI TRE and handle accordingly for functions
involving the TRE.
Process GCI evt using cookie provided by TRE instead of using the RP.
Add new enum for veid and incorporate veid to the completion_evt.

Change-Id: Id90c4b94d7e8d1e177752b71a1dec1fcb448effd
Signed-off-by: Michael Adisumarta <madisuma@codeaurora.org>