nvc0: allow to resize the code segment dynamically

nvc0: allow to resize the code segment dynamically

When an application uses a ton of shaders, we need to evict them
when the code segment is full but this is not really a good solution
if monster shaders are used because code eviction will happen a lot.

To avoid this, it seems better to dynamically resize the code
segment area after each eviction. The maximum size is arbitrary
fixed to 8MB which should be enough.

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