8390 : Replace ei_debug with msg_enable/NETIF_MSG_* feature

Removed the shared ei_debug variable. Replaced it by adding u32 msg_enable to
the private struct ei_device. Now each 8390 ethernet instance has a per-device
logging variable.

Changed older style printk() calls to more canonical forms.

Tested on: ne, ne2k-pci, smc-ultra, and wd hardware.

V4.0
- Substituted pr_info() and pr_debug() for printk() KERN_INFO and KERN_DEBUG

V3.0
- Checked for cases where pr_cont() was most appropriate choice.
- Changed module parameter from 'debug' to 'msg_enable' because debug was
no longer the best description.

V2.0
- Changed netif_msg_(drv|probe|ifdown|rx_err|tx_err|tx_queued|intr|rx_status|hw)
to netif_(dbg|info|warn|err) where possible.

Signed-off-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>