ieee1394: eth1394: fix error path in module_init

This patch fixes some error handlings in eth1394:

- check return value of kmem_cache_create()
- cleanup resources if hpsb_register_protocol() fails

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (whitespace)