[CASSINI]: sparse annotations and fixes

- __user annotations
- NULL noise removal
- C99 initializers
- s/u32/pm_message_t/ in ->suspend()
- removal of bogus casts in iounmap() arguments
- if_mii() instead of open-coded variant

Remains to be done: ethtool conversion.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>