arcnet: com20020-pci: Fix an error handling path in 'com20020pci_probe()'

If this memory allocation fails, we should go through the error handling
path as done everywhere else in this function before returning.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>