Importing usr.sbin/i2cscan

Change-Id: I7b776d6e5f3fe4f7a1af353b995ef9e2e752c7ea
libi2cdriver: library for i2c device drivers

Change-Id: Ib6d5617e4b62e0bc5b25e6fa92b44baf536b1961
cat24c256: driver for the cat24c256 i2c eeprom

Change-Id: I682d136c80fc868d3f0a5edb0cf6c33c0f3a28ea
eepromread: simple program to view eeprom contents

This program uses the i2c /dev interface to read the
contents of EEPROMs and display it to the user in
HEX and ASCII. It also has a mode that can display
data in label:value pairs. That mode is used for
board detection in the rc script to start the right
i2c drivers for the board.

Change-Id: I0bf5b13ffab5a89533c762d6881a145cf7f14914