nir: rename f2f16_undef to f2f16

we need rounding modes on other conversions involving floats and it is easier
to rename f2f16_undef than renaming all the other ones.

v2: rebased on master

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>

src/intel/compiler/brw_fs_nir.cpp

@@ -787,7 +787,7 @@ fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
        * BRW_OPCODE_F32TO16 when/if we work for HF support on gen7.
        */
 
-   case nir_op_f2f16_undef:
+   case nir_op_f2f16:
       inst = bld.MOV(result, op[0]);
       inst->saturate = instr->dest.saturate;
       break;