Add missing BB rev C free to use table, correct the BBxM one
All versions of Beagleboard were referring to a single table, but at rev C three of the GPIO pins got moved, so we need a different table for that so that the GPIO module will enumerate the right one. For Beagleboard xM, 10 pins were missing. From discussion at https://www.riscosopen.org/forum/forums/11/topics/11903?page=2#posts-97755 Tested on Beagleboard C4 and xM.