netdev_printk/netif_printk: Remove a superfluous logging colon

netdev_printk originally called dev_printk with %pV.

This style emitted the complete dev_printk header with
a colon followed by the netdev_name prefix followed
by a colon.

Now that netdev_printk does not call dev_printk, the
extra colon is superfluous.  Remove it.

Example:
old: sky2 0000:02:00.0: eth0: Link is up at 100 Mbps, full duplex, flow control both
new: sky2 0000:02:00.0 eth0: Link is up at 100 Mbps, full duplex, flow control both

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: David S. Miller <davem@davemloft.net>
Tested-by: Jim Cromie <jim.cromie@gmail.com>
Acked-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>