ipg: Use current logging styles

Add and use pr_fmt, pr_<level> and netdev_<level>.
Convert printks with %[n].[n]x to %nx to be shorter
and clearer.
Consolidate printks to use a single printk rather
than continued printks without KERN_CONT.
Removed unnecessary trailing periods.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>