ARM: dts: imx27-phytec-phycore-rdk: Remove duplicate entries for USB PHY

"compatible", "#address-cells" and "#size-cells" for USB PHY are
already described in the SOM DTS. Remove these duplicate entries.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>