[PATCH] MODALIAS= for macio

Prodive a MODALIAS= enviroment variable for devices on the mac-io bus.
Change the buffer length counter to not waste memory by advancing the
pointer for the next string too far.  Tested on an ibook1 with modular
pmac_zilog.

Signed-off-by: Olaf Hering <olh@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>