drm/amdgpu: Suspend IH during mode-2 reset

On multi-aid SOCs, there could be a continuous stream of interrupts from
GC after poison consumption. Suspend IH to disable them before doing
mode-2 reset. This avoids conflicts in hardware accesses during
interrupt handlers while a reset is ongoing.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Asad Kamal <asad.kamal@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>