intel/brw: Remove unused enum

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33251>
diff --git a/src/intel/compiler/brw_fs.h b/src/intel/compiler/brw_fs.h
index 39a0d9f..497c314 100644
--- a/src/intel/compiler/brw_fs.h
+++ b/src/intel/compiler/brw_fs.h
@@ -245,16 +245,6 @@
    void load_shader_type(const brw_builder &bld, brw_reg &dest) const;
 };
 
-enum instruction_scheduler_mode {
-   SCHEDULE_PRE,
-   SCHEDULE_PRE_NON_LIFO,
-   SCHEDULE_PRE_LIFO,
-   SCHEDULE_POST,
-   SCHEDULE_NONE,
-};
-
-class instruction_scheduler;
-
 enum brw_shader_phase {
    BRW_SHADER_PHASE_INITIAL = 0,
    BRW_SHADER_PHASE_AFTER_NIR,