tcg/loongarch64: Fix buid error

tcg/loongarch64: Fix buid error

Fix:

  In file included from ../tcg/tcg.c:735:
  /home1/gaosong/bugfix/qemu/tcg/loongarch64/tcg-target.c.inc: In function ‘tcg_out_vec_op’:
  /home1/gaosong/bugfix/qemu/tcg/loongarch64/tcg-target.c.inc:1855:9: error: a label can only be part of a statement and a declaration is not a statement
           TCGCond cond = args[3];
           ^~~~~~~

Signed-off-by: gaosong <gaosong@loongson.cn>
Message-Id: <20230926075819.3602537-1-gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>