drm/amdgpu: Disable irq on device before destroying it

Disable irq on devices before destroying them. That prevents
use-after-free memory access when unloading the driver.

Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>