bindings: python: tests: add coverage of kernel reconfigure as-is behaviour

bindings: python: tests: add coverage of kernel reconfigure as-is behaviour

The kernel's handling of reconfigure with default values, as is the
case for providing a None value as the settings to the Python bindings'
reconfigure_lines(), resets any flags set to non-default values when the
line is requested to their default values.  While the flags are cleared,
the kernel makes no corresponding change to the electrical settings -
though subsequent calls to get and set values will apply the updated
flags.

The tests for missing or None settings are extended to demonstrate the
issue for active_low and drive flags, though the issue applies to all
flags.

The tests fail unless the kernel is patched to ignore reconfiguration
of lines without direction set.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20240626053808.179457-4-warthog618@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>