drm/msm/a6xx: Handle GMU prepare-slumber hfi failure

drm/msm/a6xx: Handle GMU prepare-slumber hfi failure

[ Upstream commit d6463fd4e97545ef4f7069d13a5fa3ac0924dae2 ]

When prepare-slumber hfi fails, we should follow a6xx_gmu_force_off()
sequence.

Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/498401/
Link: https://lore.kernel.org/r/20220819015030.v5.7.I54815c7c36b80d4725cd054e536365250454452f@changeid
Signed-off-by: Rob Clark <robdclark@chromium.org>
Stable-dep-of: f561db72a663 ("drm/msm/a6xx: Fix stale rpmh votes from GPU")
Signed-off-by: Sasha Levin <sashal@kernel.org>