ac/nir/ngg: Delete unused struct.

This was left there by accident after a rebase mistake.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12246>

src/amd/common/ac_nir_lower_ngg.c

@@ -97,11 +97,6 @@ typedef struct {
    nir_variable *pos_value_replacement;
 } remove_extra_position_output_state;
 
-typedef struct {
-   nir_ssa_def *reduction_result;
-   nir_ssa_def *excl_scan_result;
-} wg_scan_result;
-
 /* Per-vertex LDS layout of culling shaders */
 enum {
    /* Position of the ES vertex (at the beginning for alignment reasons) */