fix(gpio): support Rockchip global GPIO numbering

[mitchellmoss]

Summary

• Resolve integer GPIO values >=32 to /dev/gpiochip line when the matching banked gpiochip exists.
• Preserve existing Raspberry Pi / BCM-style behavior for low GPIO line numbers and for systems without a matching banked gpiochip.
• Guard the python-periphery cdev2 realtime event-clock workaround so older python-periphery builds that do not ship gpio_cdev2 still import cleanly.

Context

Luckfox/Rockchip documentation exposes header pins as global GPIO numbers using bank * 32 + offset. PiMesh V2 / E22P configs on Luckfox use values like 54, 121, and 122; treating those as line offsets on /dev/gpiochip0 opens the wrong GPIO line. This keeps the current integer config style while allowing Rockchip banked GPIOs to resolve to the correct character device.

Verification

• python3 -m compileall -q src
• git diff --check
• python3 -m pytest -q could not run locally because pytest is not installed in the active Python environment.