usb: skip phys initialization of shared hcd

The phys has already been initialized when add primary hcd,
including usb2 phys and usb3 phys also if exist, so needn't
re-parse "phys" property again.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>