drm/amdgpu: Conditionally reset SDMA RAS error counts

Reset SDMA RAS error counts during init only if persistent
EDC harvesting is not supported.

Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: John Clements <john.clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>