msm: kgsl: Move deassert_gbif_halt to a6xx specific space

deassert_gbif_halt is needed only for the a6xx targets that use
clear_pending_transactions. So move deassert_gbif_halt to a6xx specific
space. This helps to provide some clarity and avoid gmu and gbif
related checks.

Change-Id: If46fa22a54737c2dbc35205318ed75ead351760a
Signed-off-by: Puranam V G Tejaswi <pvgtejas@codeaurora.org>