usb: host: ehci-platform: set hcd->phy to avoid phy_get() in usb_add_hcd()

This patch sets hcd->phy from own phy context to avoid phy_get()
in usb_add_hcd(). Since core/hcd.c manages the phy only in
usb_add_hcd() and usb_remove_hcd(), there is difficult to manage
the phy in suspend/resume.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>