tcg/mips: inline bswap16/bswap32 ops

Use an inline version for the bswap16 and bswap32 ops to avoid
testing for MIPS32R2 instructions availability, as these ops are
only available in that case.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

tcg/mips/tcg-target.c

@@ -1506,13 +1506,12 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
         }
         break;
 
-    /* The bswap routines do not work on non-R2 CPU. In that case
-       we let TCG generating the corresponding code. */
     case INDEX_op_bswap16_i32:
-        tcg_out_bswap16(s, args[0], args[1]);
+        tcg_out_opc_reg(s, OPC_WSBH, args[0], 0, args[1]);
         break;
     case INDEX_op_bswap32_i32:
-        tcg_out_bswap32(s, args[0], args[1]);
+        tcg_out_opc_reg(s, OPC_WSBH, args[0], 0, args[1]);
+        tcg_out_opc_sa(s, OPC_ROTR, args[0], args[0], 16);
         break;
 
     case INDEX_op_ext8s_i32: