Describe the PHY topology for all configurations supported by each board

Based on prior work by Andy Fleming <afleming@freescale.com>
Signed-off-by: NShruti Kanetkar <Shruti@freescale.com>
Signed-off-by: NEmil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: NIgal Liberman <Igal.Liberman@freescale.com>
Signed-off-by: NScott Wood <oss@buserror.net>