nir/print: Add support for generic pointers

The way they're handled is that deref->modes is treated as a bitfield of
possible modes.  Variables are required to have a specific mode and
derefs with deref_type_var are as well.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13171>

src/compiler/nir/nir_print.c

@@ -561,6 +561,8 @@ get_variable_mode_str(nir_variable_mode mode, bool want_local_global_mode)
    case nir_var_mem_task_payload:
       return "task_payload";
    default:
+      if (mode && (mode & nir_var_mem_generic) == mode)
+         return "generic";
       return "";
    }
 }