tcg/i386: fix unsigned vector saturating arithmetic

Due to a cut/paste error in the original implementation, the unsigned
vector saturating arithmetic was erroneously being calculated as signed
vector saturating arithmetic.

Fixes: 8ffafbcec2 ("tcg/i386: Implement vector saturating arithmetic")
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20190207224258.426-1-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/i386/tcg-target.inc.c

@@ -2615,7 +2615,7 @@ static void tcg_out_vec_op(TCGContext *s, TCGOpcode opc,
         OPC_PADDSB, OPC_PADDSW, OPC_UD2, OPC_UD2
     };
     static int const usadd_insn[4] = {
-        OPC_PADDSB, OPC_PADDSW, OPC_UD2, OPC_UD2
+        OPC_PADDUB, OPC_PADDUW, OPC_UD2, OPC_UD2
     };
     static int const sub_insn[4] = {
         OPC_PSUBB, OPC_PSUBW, OPC_PSUBD, OPC_PSUBQ
@@ -2624,7 +2624,7 @@ static void tcg_out_vec_op(TCGContext *s, TCGOpcode opc,
         OPC_PSUBSB, OPC_PSUBSW, OPC_UD2, OPC_UD2
     };
     static int const ussub_insn[4] = {
-        OPC_PSUBSB, OPC_PSUBSW, OPC_UD2, OPC_UD2
+        OPC_PSUBUB, OPC_PSUBUW, OPC_UD2, OPC_UD2
     };
     static int const mul_insn[4] = {
         OPC_UD2, OPC_PMULLW, OPC_PMULLD, OPC_UD2