ir3: fix shift amount for 8-bit shifts

Follow the 16-bit approach and convert shift amount to 8b for 8b shift
instructions.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26817>
1 file changed