net: marvell: prestera: fix error return code in prestera_pci_probe()

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

Fixes: 4c2703df ("net: marvell: prestera: Add PCI interface support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Reviewed-by: Vadym Kochan <vadym.kochan@plvision.eu>
Acked-by: Vadym Kochan <vadym.kochan@plvision.eu>
Link: https://lore.kernel.org/r/20201113113236.71678-1-wanghai38@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>