drivers/net/cassini.c: Use (pr|netdev|netif)_<level> macro helpers

Add #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
Remove #define PFX
Use pr_<level>
Use netdev_<level>
Use netif_<level>
Remove periods from formats
Coalesce long formats
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>