USB: core: hcd: drop support for legacy phys

Drop support for looking up and initialising legacy phys in USB core,
something which hasn't been used by a mainline kernel since commit
9080b8dc

 ("ARM: OMAP2+: Remove legacy usb-host.c platform init
code"). Specifically, since that commit usb_get_phy_dev() have always
returned -ENODEV and consequently this code has not been used.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>