st/nine: Convert integer constants to floats before storing them when cards don't support integers

The shader code is already behaving as if they are floats when the the card doesn't support integers

Signed-off-by: Axel Davy <axel.davy@ens.fr>
st/nine: Use integers for loops when available

Signed-off-by: Axel Davy <axel.davy@ens.fr>
st/nine: simplify NineDevice9_RestoreNonCSOState

Let nine_update_state do the job

Signed-off-by: Axel Davy <axel.davy@ens.fr>
st/nine: Use several constant buffers when possible

Signed-off-by: Axel Davy <axel.davy@ens.fr>