Let boards only define the port and pin number of each LEDs. The common
definitions in `stm32_leds.h` will provide `LED<x>_ON`, `LED<x>_OFF`,
`LED<x>_TOGGLE`, `LED<x>_PIN`, `LED<x>_MASK` and `LED<x>_PORT`.
In addition to code de-duplication, this also makes it easier to use
LEDs in GPIO LL, which can be beneficial for super low overhead
debugging output - e.g. when a bug is timing sensitive and `DEBUG()`
would spent to much time for stdio to reproduce a bug.
Add motor_driver driver configuration example.
The most simple motor driver type is used here (MOTOR_DRIVER_1_DIR) which
needs only one pin to work.
This example uses already configured PWM channels and 2 free GPIOS.
Signed-off-by: Gilles DOFFE <g.doffe@gmail.com>
