drm/amdgpu: Fix pci state save during mode-1 reset

Cache the PCI state before bus master is disabled. The saved state is
later used for other cases like restoring config space after mode-2
reset.

Fixes: 5c03e584

 ("drm/amdgpu:add smu mode1/2 support for aldebaran")
Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>