Made a few minor changes to adjust for
NxM matrices in assembly output.

Change-Id: I3dde37e0f4bd2623232eebf0dc06182d8071d751
Reviewed-on: https://swiftshader-review.googlesource.com/2863Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>