bsd-user: Add missing break after do_bsd_preadv

Without it, we'd call preadv, then write with weird parameters, which is
clearly not ideal...

Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Fixes: 770d8abae7 ("bsd-user/bsd-file.h: Meat of the write system calls")
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230820045419.89691-1-imp@bsdimp.com>

bsd-user/freebsd/os-syscall.c

@@ -240,6 +240,7 @@ static abi_long freebsd_syscall(void *cpu_env, int num, abi_long arg1,
 
     case TARGET_FREEBSD_NR_preadv: /* preadv(2) */
         ret = do_bsd_preadv(cpu_env, arg1, arg2, arg3, arg4, arg5, arg6);
+        break;
 
     case TARGET_FREEBSD_NR_write: /* write(2) */
         ret = do_bsd_write(arg1, arg2, arg3);