intel/compiler: add setup_imm_(u)b helpers

The hardware doesn't support byte immediates, so similar to setup_imm_df()
for doubles, these helpers work by loading the constant value into a
VGRF.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/intel/compiler/brw_fs.h

@@ -540,6 +540,12 @@ fs_reg shuffle_for_32bit_write(const brw::fs_builder &bld,
 fs_reg setup_imm_df(const brw::fs_builder &bld,
                     double v);
 
+fs_reg setup_imm_b(const brw::fs_builder &bld,
+                   int8_t v);
+
+fs_reg setup_imm_ub(const brw::fs_builder &bld,
+                   uint8_t v);
+
 enum brw_barycentric_mode brw_barycentric_mode(enum glsl_interp_mode mode,
                                                nir_intrinsic_op op);