power_controller: read gpio pins from device tree

power_controller: read gpio pins from device tree

This commit is part of the effort to move configuration of hardware more
closely to the linux platform

• [DH] src/app/bmc_application.rs
• [DH] src/authentication/authentication_errors.rs
• [DH] src/hal/gpio_definitions.rs
• [DH] src/hal/helpers.rs
• [DH] src/hal/power_controller.rs
• [DH] src/serial_service.rs