Lirc gpio driver

This adds a driver that can be used in conjunction with Lirc to send and receive IR pulses using GPIO pins, much like one can do with lirc_serial (this driver ported from lirc_rpi). Works for me for both sending and receiving.
Circuit is below (I will make a proper forum post about it and the configuration with lirc) - note that the Receiver pins may be different than the symbol I found. Pull up resistor is enabled in the driver, so diode protects from 5V.

Kernel config that I use. There are module options for changing which pins are used.
```
CONFIG_LIRC=y
CONFIG_IR_LIRC_CODEC=y
CONFIG_LIRC_STAGING=y
CONFIG_LIRC_ODROID=m
```

![ircircuit](https://f.cloud.github.com/assets/1788847/1236250/001741ba-29bb-11e3-8f43-96c9a4f2b7e8.png)