drivers/net/tg3.c: Use (pr|netdev)_<level> macro helpers

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