nubus: Clean up printk calls

Some long forgotten changes from the linux-mac68k CVS:

Fix swapped DrvrSW and DrvrHW values in printk message.
Suppress debug printk messages.
Avoid console_loglevel misuse.

The original commits are these:

http://linux-mac68k.cvs.sourceforge.net/viewvc/linux-mac68k/linux-mac68k/drivers/nubus/nubus.c?r1=1.22.2.1&r2=1.22.2.2&pathrev=linux-2_2
http://linux-mac68k.cvs.sourceforge.net/viewvc/linux-mac68k/linux-mac68k/drivers/nubus/nubus.c?r1=1.21&r2=1.22&pathrev=linux-2_2

The CVS commits fell short of removing all of the misuse of
console_loglevel in nubus_add_board() so I finished the job.
I've also added some missing message severity levels and converted
a printk loop to the MAC address "%pM" format specifier.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>