bat.d driver: Dell laptops (dell_laptop)

    * Supports Dell laptops
    * Requires dell_laptop module as of Linux 6.11
    * Start and stop threshold
    * Force discharge not supported

    * charge_control_start_threshold:
      - Valid values: 50..95
      - Default value: 95

    * charge_control_end_threshold:
      - Valid values: 55..100
      - Default value: 100

References:
* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/platform/x86/dell?id=ab58016c68cc5b8c3622e38b7db64994e4833d9f
* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/platform/x86/dell/dell-laptop.c
* #379 (comment)