[PATCH] get_dev_number() in extras/ide-devfs.sh

this patch corrects ide devices with number greater than 9 being linked
into wrong discs/discX directories (my hda10 device was in discs/disc1
directory)
it adds % into pattern for $DRIVE, so for example, hda10 is not eaten
to hda1, but to hda, and break in for cycle works for it