drm/amdgpu/vcn: reset fw_shared when VCPU buffers corrupted on vcn v4.0.3

[ Upstream commit 928cd772 ]

It is not necessarily corrupted. When there is RAS fatal error, device
memory access is blocked. Hence vcpu bo cannot be saved to system memory
as in a regular suspend sequence before going for reset. In other full
device reset cases, that gets saved and restored during resume.

v2: Remove redundant code like vcn_v4_0 did
v2: Refine commit message
v3: Drop the volatile
v3: Refine commit message

Signed-off-by: Xiang Liu <xiang.liu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Stanley.Yang <Stanley.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>