drm/amdgpu: Don't do FB resize under A+A config

Disable PCIe BAR resizing on A+A config. It's not needed because we won't use the
PCIe BAR, but it breaks the PCI BAR configuration with the current SBIOS.

Error message of FB BAR resize failure under A+A:

[  154.913731] [drm:amdgpu_device_resize_fb_bar [amdgpu]] *ERROR* Problem resizing BAR0 (-22).

Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>
Reviewed-by: Amber Lin <Amber.Lin@amd.com>
Reviewed-by: Felix Kuehling <Felix.kuehling@amd.com>
Reviewed-by: Christian Koenig <Christian.Koenig@amd.com>
Tested-by: Amber Lin <Amber.Lin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>