intel/compiler: Silence unused parameter warnings

intel/compiler: Silence unused parameter warnings

src/intel/compiler/brw_disasm_info.c: In function ‘nir_print_instr’:
src/intel/compiler/brw_disasm_info.c:30:61: warning: unused parameter ‘instr’ [-Wunused-parameter]
 __attribute__((weak)) void nir_print_instr(const nir_instr *instr, FILE *fp) {}
                                                             ^~~~~
src/intel/compiler/brw_disasm_info.c:30:74: warning: unused parameter ‘fp’ [-Wunused-parameter]
 __attribute__((weak)) void nir_print_instr(const nir_instr *instr, FILE *fp) {}
                                                                          ^~
src/intel/compiler/brw_disasm.c: In function ‘src_ia1’:
src/intel/compiler/brw_disasm.c:850:18: warning: unused parameter ‘_reg_file’ [-Wunused-parameter]
         unsigned _reg_file,
                  ^~~~~~~~~
src/intel/compiler/brw_fs_surface_builder.cpp: In function ‘void brw::surface_access::emit_byte_scattered_write(const brw::fs_builder&, const fs_reg&, const fs_reg&, const fs_reg&, unsigned int, unsigned int, unsigned int, brw_predicate)’:
src/intel/compiler/brw_fs_surface_builder.cpp:193:57: warning: unused parameter ‘size’ [-Wunused-parameter]
                                 unsigned dims, unsigned size,
                                                         ^~~~

v2: Update commit message.  brw_fs_generator.cpp warnings were already
fixed by another patch.  Noticed by Caio.

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