Investigate if the 2711 has a different mechanism for pin pull-up/down/enable

[jonlamb-gh]

• https://github.com/RPi-Distro/raspi-gpio/blob/master/raspi-gpio.c#L194
• https://github.com/rsta2/circle/blob/fe24b6bebd1532f2a0ee981af12eaf50cc9e97fb/include/circle/bcm2835.h#L73
• https://github.com/rsta2/circle/blob/fe24b6bebd1532f2a0ee981af12eaf50cc9e97fb/lib/gpiopin.cpp#L350