USB: move transceiver from ehci_hcd and ohci_hcd to hcd and rename it as phy

 - to decrease redundant since both ehci_hcd and ohci_hcd have the same variable
 - it helps access phy in usb core code
 - phy is more meaningful than transceiver

Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>