drm/amdgpu: Drop pcie_bif ras check from fatal error handler

Some ASICs support fatal error event but do not
support pcie_bif ras.

Signed-off-by: Candice Li <candice.li@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>