arm64: defconfig: enable nop-xceiv PHY driver

This commit enables the nop-xceiv PHY driver, which is needed for USB
support to work on the MacchiatoBin platform (Marvell Armada 8K).

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>