drm/amdgpu: handle ras resume

Suspend will put irq, so resume need get irq back.
And in the same time, skip other ras initialization.

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