msm: ipa3: WA for incorrect state retention for GSI channel 20

This change in a software workaround for a hardware limitation
to not use GSI channel 20.

CRs-Fixed: 1005061
Change-Id: I4ed9f1c6ad089f80dcd19762fda151ce1572f471
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>