mx53qsb uses GPIO7_8 to turn on VBUS, so add support for it.

Also specify the PHY type in the device tree.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Tested-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>