radv,aco,ac/llvm: fix indirect dispatches on the compute queue on GFX7-10

Since neither PKT3_LOAD_SH_REG_INDEX nor PKT3_COPY_DATA work with compute
queues on GFX7-10, we have to load the dispatch size from memory in the
shader.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15064>

src/amd/llvm/ac_shader_abi.h

@@ -175,6 +175,9 @@ struct ac_shader_abi {
     * images.
     */
    bool disable_aniso_single_level;
+
+   /* Whether to inline the compute dispatch size in user sgprs. */
+   bool load_grid_size_from_user_sgpr;
 };
 
 #endif /* AC_SHADER_ABI_H */