drm/amdgpu: Resolve RAS GFX error count issue v2

Fix misleading indentation and add ras unsupported checking
for gfx ras late init.

Fixes: fd3fb1b9 ("drm/amdgpu: Resolve RAS GFX error count issue after cold boot on Arcturus")
Signed-off-by: Candice Li <candice.li@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>