[PATCH] m68knommu: use THREAD_SIZE instead of hard coded size

Use the THREAD_SIZE define when manipulating the stack instead of
hard coded values (for the 68328 and 68360 sub-architectures).

Signed-off-by: Greg Ungerer <gerg@uclinux.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>