Commit cf7c93cdd7 "usb: ehci: Implement V2P mapping"
introduced usage of virt_to_phys() in ehci-hcd.
Since there was no implementation of virt_to_phys() for ARC
compilation of the ehci-generic driver failed.
This change adds virt_to_phys() stub for ARC so now
USB driver for AXS101 board could be built again.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Acked-by: Marek Vasut <marex@denx.de>