agx: allow phis with 16bit imms

could do 32-bit too..

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26963>

src/asahi/compiler/agx_ir.c

@@ -10,5 +10,6 @@ agx_allows_16bit_immediate(agx_instr *I)
 {
    return (I->op == AGX_OPCODE_DEVICE_LOAD) ||
           (I->op == AGX_OPCODE_DEVICE_STORE) ||
-          (I->op == AGX_OPCODE_UNIFORM_STORE) || (I->op == AGX_OPCODE_ATOMIC);
+          (I->op == AGX_OPCODE_UNIFORM_STORE) || (I->op == AGX_OPCODE_ATOMIC) ||
+          (I->op == AGX_OPCODE_PHI);
 }