drm/amdgpu: correct SE number for arcturus gfx ras

When resetting EDC related register, all CUs needs to be visited,
otherwise, garbage data from EDC register of missed SEs would present.

Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Dennis Li <Dennis.Li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>