quantizer: fix assertion in fast quantizer path

The fast quantizer assembly code has not been updated to match the new
exact quantizer, which was made the default in commit 6adbe090.
Specifically, they are not aware of the potential for the coefficient
to be scaled, which results in the quantized result exceeding the range
of the DCT. This patch restores the previous behavior of using the
non-shifted coefficients when in the fast quantizer code path, but
unfortunately requires rebuilding the tables when switching between the
two.

Change-Id: I0a33f5b3850335011a06906f49fafed54dda9546