board/common: Add support for QIXIS read/write using i2c

QIXIS FPGA is accessable via both i2c and flash controller.
Only flash controller access is supported.

Add support of i2c based access. It is quite useful in the scenario
where either flash controller path is broken or not present.

Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>