netduiunoplus2: Update the number of GPIO lines to 16

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_timer: Tidy up PWM

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_adc: Remove the rand function if it's not supported

Signed-off-by: Alistair Francis <alistair23@gmail.com>