wan: pc300too: abort path on failure

In function pc300_pci_init_one(), on the ioremap error path, function
pc300_pci_remove_one() is called to free the allocated memory. However,
the path is not terminated, and the freed memory will be used later,
resulting in use-after-free bugs. This path fixes the bug.

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>