aco/wave32: Allow setting the subgroup ballot size to 64-bit.

Previously, it would only work when the ballot size was set to the
lane mask. This patch makes is possible to set the ballot size
to either 32-bit or 64-bit for wave32 mode.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>

src/amd/compiler/aco_instruction_selection_setup.cpp

@@ -294,7 +294,6 @@ void init_context(isel_context *ctx, nir_shader *shader)
                      break;
                   case nir_intrinsic_ballot:
                      type = RegType::sgpr;
-                     size = lane_mask_size;
                      break;
                   case nir_intrinsic_load_sample_id:
                   case nir_intrinsic_load_sample_mask_in: