Add an entry for the optional 'phy-clkgate-delay-us' property that is
used to describe the delay time between putting PHY into low power
mode and turning off the PHY clock.
Signed-off-by: NLi Jun <jun.li@freescale.com>
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NPeter Chen <peter.chen@freescale.com>