Remove unused and unneeded functions, also create Pin.get_config() that
returns the whole configuration of the pin.
This reduces code size by ~500 bytes.
This change helps making the cc3200 port API a bit closer to stmhal.
The ramaining differences are due to the specific hardware details
of each chip. One feature that has been deliberately disabled is the
possibility to add custom names and custom pin mappings. Those
features are nice and convenient, but in this port, code size is a
major concern.
