radv/gfx10: declare a LDS symbol for the NGG emit space

This fixes some interactions when NGG GS is enabled. It fixes:

- dEQP-VK.clipping.user_defined.clip_cull_distance_dynamic_index.*geom*
- dEQP-VK.tessellation.geometry_interaction.passthrough.*

For some reasons, using the computed ESGS ring size randomly hangs
with CTS. For now, just use the maximum LDS size for ESGS.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>