USB: EHCI: ehci-mv: make the PHY optional

We may be using a NOP transceiver and those are treated specially by the
USB core and return -ENODEV with devm_phy_get().

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20191221065008.266445-3-lkundrak@v3.sk


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>