drivers/net/e100.c: Use pr_<level> and netif_<level>

Convert DPRINTK, commonly used for debugging, to netif_<level>
Remove #define PFX
Use #define pr_fmt
Consistently use no periods for non-sentence logging messages
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>