drm/amdgpu/si: add need_reset_on_init asic callback for SI (v2)

SI chips don't require a reset on reload due to the nature of
the SMU on them.

v2: rebase

Reviewed-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>