PCI: loongson: Simplify loongson_pci_probe() return expression

Simplify the return expression.

Link: https://lore.kernel.org/r/20200921131054.92797-1-miaoqinglang@huawei.com


Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>