to flush the TLB instead of hardcoding a size of 33 pages. Apertures of
32MB and 64MB only use a 16 page GATT and an aperture of 128MB only uses
a 32 page GATT, so without this the code could walk off the end of the
pointer and cause a page fault if the next page was unmapped. Also, for
aperture sizes > 128MB, not all of the pages would be read. The Linux
driver has the same bug.
MFC after: 1 week
Tested by: Frédéric PRACA frederic.praca of freebsd-fr.org
ce6d690203