ENGR00176812-9 mx6 sabreauto: add revB board support

ENGR00176812-9 mx6 sabreauto: add revB board support

* mx6 sabreauto revB include a steering logic
  circuit that enables the route path for i2c3_sda signal.
  This patch enables i2c3_sda route to fix io-expander
  read/write errors and additional devices connected to
  the i2c3 bus.
* mx6 sabreauto revB board uses atheors fec phy.
* Set GPIO_16 as input for IEEE-1588 ts_clk and RMII
  reference clk

Signed-off-by: Adrian Alonso <aalonso@freescale.com>