drm/msm/adreno: fix cast in adreno_get_param()

These casts need to happen before the shift.  The only time it would
matter would be if "rev.core" is >= 128.  In that case the sign bit
would be extended and we do not want that.

Fixes: afab9d91

 ("drm/msm/adreno: Expose speedbin to userspace")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Link: https://lore.kernel.org/r/20220307133105.GA17534@kili
Signed-off-by: Rob Clark <robdclark@chromium.org>