Generic I2C support for LininoIO

This change adds generic I2C support for LininoIO but can be used with other Linux distros.
As part of this change the I2C APIs have been streamlined.

Change-Id: If7de508ad4c92a4f694aa2e22e4fa5f874e3396f
Signed-off-by: Greg Burns <gburns@qce.qualcomm.com>