With the new beta boards, for those users who don't need an SDCard for
their project, it would be great to allow them to use the 6 IO pins
associated with the SDCARD for other purposes. This would probably
require a cheap adapter, but these are nice signals to be able to be
used. They include:
SPI1: SCK, MISO, MOSI, CS0-2
Serail2: TX/RX
Serial4: TX/RX
I2C1: SCL/SDA
This change adds support for GPIO, SPI, Serial2 and Serial4