drm/amdgpu: Enabling FW workaround through shared memory for VCN4_0_2

This patch will enable VCN FW workaround using
DRM KEY INJECT WORKAROUND method,
which is helping in fixing the secure playback.

Signed-off-by: sguttula <Suresh.Guttula@amd.com>
Reviewed-by: Leo Liu <leo.liiu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>