intel/compiler: Silence unused parameter warnings brw_nir.c

intel/compiler: Silence unused parameter warnings brw_nir.c

src/intel/compiler/brw_nir.c: In function ‘brw_nir_lower_vue_outputs’:
src/intel/compiler/brw_nir.c:464:32: warning: unused parameter ‘is_scalar’ [-Wunused-parameter]
                           bool is_scalar)
                                ^~~~~~~~~
src/intel/compiler/brw_nir.c: In function ‘lower_bit_size_callback’:
src/intel/compiler/brw_nir.c:610:57: warning: unused parameter ‘data’ [-Wunused-parameter]
 lower_bit_size_callback(const nir_alu_instr *alu, void *data)
                                                         ^~~~

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>