intel/compiler: Remove unnecessary local variables

These are already provided in the fs_reg_alloc class.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4093>

src/intel/compiler/brw_fs_reg_allocate.cpp

@@ -719,9 +719,6 @@ fs_reg_alloc::setup_inst_interference(fs_inst *inst)
 void
 fs_reg_alloc::build_interference_graph(bool allow_spilling)
 {
-   const gen_device_info *devinfo = fs->devinfo;
-   const brw_compiler *compiler = fs->compiler;
-
    /* Compute the RA node layout */
    node_count = 0;
    first_payload_node = node_count;