nvc0: increase the tex handles area size in the driver cb

nvc0: increase the tex handles area size in the driver cb

Currently, we can store 32 tex handles of 32-bits integer each and
that fits perfectly with the underlying hardware except on GM107+
which requires to upload a texture view for each images.

This patch increases the number of storable texture handles in the
driver constant buffer from 32 to 40 because we expose 8 images.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>