This uses an equivalent algorithm but with a different initial value
than we normally use (all bits off vs all bits on). Use the new crc_32r
to replace the original MI4 crc32 implementation.
This frees up some extra space on mi4 targets which gives us more
room on a few very space constrained targets (sansa c200/e200, etc).
Change-Id: Iaaac3ae353b30566156b1404cbf31ca32926203d
581081a3df