Fix to return negative error code -ENODEV from the unsupported revision
error handling case instead of 0, as done elsewhere in this function.

Link: https://lore.kernel.org/r/20210308135619.19133-1-weiyongjun1@huawei.com
Fixes: 0cdfaceb ("PCI: brcmstb: support BCM4908 with external PERST# signal controller")
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: NKrzysztof Wilczyński <kw@linux.com>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>