tcg/riscv: Fix StoreStore barrier generation

On RISC-V to StoreStore barrier corresponds
`fence w, w` not `fence r, r`

Cc: qemu-stable@nongnu.org
Fixes: efbea94c76b ("tcg/riscv: Add slowpath load and store instructions")
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Denis Tomashev <denis.tomashev@syntacore.com>
Signed-off-by: Roman Artemev <roman.artemev@syntacore.com>
Message-ID: <e2f2131e294a49e79959d4fa9ec02cf4@syntacore.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/riscv/tcg-target.c.inc

@@ -1624,7 +1624,7 @@ static void tcg_out_mb(TCGContext *s, TCGArg a0)
         insn |= 0x02100000;
     }
     if (a0 & TCG_MO_ST_ST) {
-        insn |= 0x02200000;
+        insn |= 0x01100000;
     }
     tcg_out32(s, insn);
 }