bindings: cxx: tests: set direction when reconfiguring lines

bindings: cxx: tests: set direction when reconfiguring lines

Linux kernel commit b44039638741 ("gpiolib: cdev: Ignore reconfiguration
without direction") made the direction setting mandatory for line config
passed to the kernel when reconfiguring requested lines. Fix the C++ test
case which doesn't do it and now fails due to the rest of the settings
being ignored.

Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20240708094827.84986-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>