Now as tgetattr() is using a declarative approach, simplify the
code of callers of this function.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Message-Id: <60c6a083f320b86f3172951445df7bbc895932e2.1664917004.git.qemu_oss@crudebyte.com>