tcg: properly check that op's output needs to be synced to memory

Fix typo introduced in b3a1be87bac3a6aaa59bb88c1410f170dc9b22d5.

Reported-by: Ruslan Savchenko <ruslan.savchenko@gmail.com>
Signed-off-by: Kirill Batuzov <batuzovk@ispras.ru>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
