selftests: gpio: gpio-sim: Fix missing chip disablements

Since upstream commit 8bd76b3d ("gpio: sim: lock up configfs that an
instantiated device depends on"), rmdir for an active virtual devices
been prohibited.

Update gpio-sim selftest to align with the change.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202501221006.a1ca5dfa-lkp@intel.com


Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Link: https://lore.kernel.org/r/20250122043309.304621-1-koichiro.den@canonical.com


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>