drm/amdgpu: Enable gmc soft reset on gmc_v11_0_3

Enable gmc soft reset on gmc_v11_0_3.

Signed-off-by: YiPeng Chai <YiPeng.Chai@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>