usb: phy: jz4770: Remove driver

This driver has been replaced by the Ingenic PHY driver that uses the
generic PHY framework.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20221026182657.146630-8-paul@crapouillou.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>