agx: Handle f2f16_rtne like f2f16

TBD whether we can control round modes later on.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24635>

src/asahi/compiler/agx_compile.c

@@ -1249,6 +1249,7 @@ agx_emit_alu(agx_builder *b, nir_alu_instr *instr)
       TRIOP(ffma, fma);
 
       UNOP(f2f16, fmov);
+      UNOP(f2f16_rtne, fmov);
       UNOP(f2f32, fmov);
       UNOP(fround_even, roundeven);
       UNOP(ftrunc, trunc);